Gulfport Energy (GPOR) 10-Q 1 Nov 18 2018 Q3 Quarterly report Financial data

DOCUMENT AND ENTITY INFORMATION

DOCUMENT AND ENTITY INFORMATION - shares	9 Months Ended
	Sep. 30, 2018	Oct. 29, 2018
Document And Entity Information [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Sep. 30, 2018
Entity Registrant Name	GULFPORT ENERGY CORP
Entity Central Index Key	874,499
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2,018
Entity Filer Category	Large Accelerated Filer
Document Fiscal Period Focus	Q3
Entity Emerging Growth Company	false
Entity Small Business	false
Entity Common Stock, Shares Outstanding (in shares)		173,302,055

CONSOLIDATED BALANCE SHEETS (UN

CONSOLIDATED BALANCE SHEETS (UNAUDITED) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Current assets:
Cash and cash equivalents	$ 124,571	$ 99,557
Accounts receivable—oil and natural gas sales	157,391	146,773
Accounts receivable—joint interest and other	39,511	35,440
Accounts receivable—related parties	79	0
Prepaid expenses and other current assets	9,742	4,912
Short-term derivative instruments	19,809	78,847
Total current assets	351,103	365,529
Property and equipment:
Oil and natural gas properties, full-cost accounting, $2,925,145 and $2,912,974 excluded from amortization in 2018 and 2017, respectively	9,936,714	9,169,156
Other property and equipment	92,388	86,754
Accumulated depletion, depreciation, amortization and impairment	(4,506,306)	(4,153,733)
Property and equipment, net	5,522,796	5,102,177
Other assets:
Equity investments	232,529	302,112
Long-term derivative instruments	3,530	8,685
Deferred tax asset	0	1,208
Inventories	8,234	8,227
Other assets	17,038	19,814
Total other assets	261,331	340,046
Total assets	6,135,230	5,807,752
Current liabilities:
Accounts payable and accrued liabilities	582,464	553,609
Asset retirement obligation—current	120	120
Short-term derivative instruments	62,601	32,534
Current maturities of long-term debt	647	622
Total current liabilities	645,832	586,885
Long-term derivative instruments	15,101	2,989
Asset retirement obligation—long-term	78,411	74,980
Deferred tax liability	3,046	0
Other non-current liabilities	0	2,963
Long-term debt, net of current maturities	2,100,825	2,038,321
Total liabilities	2,843,215	2,706,138
Commitments and contingencies (Note 9)
Preferred stock, $.01 par value; 5,000,000 authorized, 30,000 authorized as redeemable 12% cumulative preferred stock, Series A; 0 issued and outstanding	0	0
Stockholders’ equity:
Common stock - $.01 par value, 200,000,000 authorized, 173,218,643 issued and outstanding at September 30, 2018 and 183,105,910 at December 31, 2017	1,732	1,831
Paid-in capital	4,316,006	4,416,250
Accumulated other comprehensive loss	(46,354)	(40,539)
Retained deficit	(979,369)	(1,275,928)
Total stockholders’ equity	3,292,015	3,101,614
Total liabilities and stockholders’ equity	6,135,230	5,807,752
Eliminations
Current assets:
Cash and cash equivalents	0	0
Accounts receivable—oil and natural gas sales	0	0
Accounts receivable—joint interest and other	0	0
Accounts receivable—related parties	0
Prepaid expenses and other current assets	0	0
Short-term derivative instruments	0	0
Total current assets	(902,692)	(617,813)
Property and equipment:
Oil and natural gas properties, full-cost accounting, $2,925,145 and $2,912,974 excluded from amortization in 2018 and 2017, respectively	(729)	(729)
Other property and equipment	0	0
Accumulated depletion, depreciation, amortization and impairment	0	0
Property and equipment, net	(729)	(729)
Other assets:
Equity investments	(2,543,991)	(2,194,848)
Long-term derivative instruments	0	0
Deferred tax asset		0
Inventories	0	0
Other assets	0	0
Total other assets	(2,543,991)	(2,194,848)
Total assets	(3,447,412)	(2,813,390)
Current liabilities:
Accounts payable and accrued liabilities	0	(1)
Asset retirement obligation—current	0	0
Short-term derivative instruments	0	0
Current maturities of long-term debt	0	0
Total current liabilities	(902,692)	(617,814)
Long-term derivative instruments	0	0
Asset retirement obligation—long-term	0	0
Deferred tax liability	0
Other non-current liabilities		0
Long-term debt, net of current maturities	0	0
Total liabilities	(902,692)	(617,814)
Stockholders’ equity:
Common stock - $.01 par value, 200,000,000 authorized, 173,218,643 issued and outstanding at September 30, 2018 and 183,105,910 at December 31, 2017	0	0
Paid-in capital	(2,177,224)	(2,174,905)
Accumulated other comprehensive loss	44,338	38,593
Retained deficit	(411,834)	(59,264)
Total stockholders’ equity	(2,544,720)	(2,195,576)
Total liabilities and stockholders’ equity	(3,447,412)	(2,813,390)
Guarantors | Reportable legal entities
Current assets:
Cash and cash equivalents	35,357	31,649
Accounts receivable—oil and natural gas sales	45,928	34,087
Accounts receivable—joint interest and other	20,445	20,005
Accounts receivable—related parties	0
Prepaid expenses and other current assets	2,221	193
Short-term derivative instruments	0	0
Total current assets	344,324	149,308
Property and equipment:
Oil and natural gas properties, full-cost accounting, $2,925,145 and $2,912,974 excluded from amortization in 2018 and 2017, respectively	2,934,047	2,607,738
Other property and equipment	751	43
Accumulated depletion, depreciation, amortization and impairment	(39)	(37)
Property and equipment, net	2,934,759	2,607,744
Other assets:
Equity investments		77,744
Long-term derivative instruments	0	0
Deferred tax asset		0
Inventories	1,434	2,411
Other assets	4,020	7,331
Total other assets	5,454	87,486
Total assets	3,284,537	2,844,538
Current liabilities:
Accounts payable and accrued liabilities	118,038	137,361
Asset retirement obligation—current	0	0
Short-term derivative instruments	0	0
Current maturities of long-term debt	0	0
Total current liabilities	780,292	691,674
Long-term derivative instruments	0	0
Asset retirement obligation—long-term	12,777	11,839
Deferred tax liability	0
Other non-current liabilities		2,963
Long-term debt, net of current maturities	0	0
Total liabilities	793,069	706,476
Stockholders’ equity:
Common stock - $.01 par value, 200,000,000 authorized, 173,218,643 issued and outstanding at September 30, 2018 and 183,105,910 at December 31, 2017	0	0
Paid-in capital	1,915,598	1,915,598
Accumulated other comprehensive loss	0	0
Retained deficit	575,870	222,464
Total stockholders’ equity	2,491,468	2,138,062
Total liabilities and stockholders’ equity	3,284,537	2,844,538
Non-Guarantor | Reportable legal entities
Current assets:
Cash and cash equivalents	0	0
Accounts receivable—oil and natural gas sales	0	0
Accounts receivable—joint interest and other	0	0
Accounts receivable—related parties	0
Prepaid expenses and other current assets	0	0
Short-term derivative instruments	0	0
Total current assets	0	0
Property and equipment:
Oil and natural gas properties, full-cost accounting, $2,925,145 and $2,912,974 excluded from amortization in 2018 and 2017, respectively	0	0
Other property and equipment	0	0
Accumulated depletion, depreciation, amortization and impairment	0	0
Property and equipment, net	0	0
Other assets:
Equity investments	53,380	57,641
Long-term derivative instruments	0	0
Deferred tax asset		0
Inventories	0	0
Other assets	0	0
Total other assets	53,380	57,641
Total assets	53,380	57,641
Current liabilities:
Accounts payable and accrued liabilities	0	0
Asset retirement obligation—current	0	0
Short-term derivative instruments	0	0
Current maturities of long-term debt	0	0
Total current liabilities	128	127
Long-term derivative instruments	0	0
Asset retirement obligation—long-term	0	0
Deferred tax liability	0
Other non-current liabilities		0
Long-term debt, net of current maturities	0	0
Total liabilities	128	127
Stockholders’ equity:
Common stock - $.01 par value, 200,000,000 authorized, 173,218,643 issued and outstanding at September 30, 2018 and 183,105,910 at December 31, 2017	0	0
Paid-in capital	261,626	259,307
Accumulated other comprehensive loss	(44,338)	(38,593)
Retained deficit	(164,036)	(163,200)
Total stockholders’ equity	53,252	57,514
Total liabilities and stockholders’ equity	53,380	57,641
Parent | Reportable legal entities
Current assets:
Cash and cash equivalents	89,214	67,908
Accounts receivable—oil and natural gas sales	111,463	112,686
Accounts receivable—joint interest and other	19,066	15,435
Accounts receivable—related parties	79
Prepaid expenses and other current assets	7,521	4,719
Short-term derivative instruments	19,809	78,847
Total current assets	909,471	834,034
Property and equipment:
Oil and natural gas properties, full-cost accounting, $2,925,145 and $2,912,974 excluded from amortization in 2018 and 2017, respectively	7,003,396	6,562,147
Other property and equipment	91,637	86,711
Accumulated depletion, depreciation, amortization and impairment	(4,506,267)	(4,153,696)
Property and equipment, net	2,588,766	2,495,162
Other assets:
Equity investments	2,723,140	2,361,575
Long-term derivative instruments	3,530	8,685
Deferred tax asset		1,208
Inventories	6,800	5,816
Other assets	13,018	12,483
Total other assets	2,746,488	2,389,767
Total assets	6,244,725	5,718,963
Current liabilities:
Accounts payable and accrued liabilities	464,426	416,249
Asset retirement obligation—current	120	120
Short-term derivative instruments	62,601	32,534
Current maturities of long-term debt	647	622
Total current liabilities	768,104	512,898
Long-term derivative instruments	15,101	2,989
Asset retirement obligation—long-term	65,634	63,141
Deferred tax liability	3,046
Other non-current liabilities		0
Long-term debt, net of current maturities	2,100,825	2,038,321
Total liabilities	2,952,710	2,617,349
Stockholders’ equity:
Common stock - $.01 par value, 200,000,000 authorized, 173,218,643 issued and outstanding at September 30, 2018 and 183,105,910 at December 31, 2017	1,732	1,831
Paid-in capital	4,316,006	4,416,250
Accumulated other comprehensive loss	(46,354)	(40,539)
Retained deficit	(979,369)	(1,275,928)
Total stockholders’ equity	3,292,015	3,101,614
Total liabilities and stockholders’ equity	$ 6,244,725	$ 5,718,963

CONSOLIDATED BALANCE SHEETS (_2

CONSOLIDATED BALANCE SHEETS (UNAUDITED) (PARENTHETICAL) - USD ($) $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2018	Dec. 31, 2017
Statement of Financial Position [Abstract]
Capitalized costs of oil and natural gas properties excluded from amortization	$ 2,925,145	$ 2,912,974
Preferred stock, par value (in usd per share)	$ 0.01	$ 0.01
Preferred stock, shares authorized (in shares)	5,000,000	5,000,000
Preferred stock, dividend rate	12.00%	12.00%
Preferred stock, shares authorized (in shares)	30,000	30,000
Preferred stock Series A, issued (in shares)	0	0
Preferred stock Series A, outstanding (in shares)	0	0
Common stock, par value (in usd per share)	$ 0.01	$ 0.01
Common stock, shares authorized (in shares)	200,000,000	200,000,000
Common stock, shares, issued (in shares)	173,218,643	183,105,910
Common stock, shares, outstanding (in shares)	173,218,643	183,105,910

CONSOLIDATED STATEMENTS OF OPER

CONSOLIDATED STATEMENTS OF OPERATIONS (UNAUDITED) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Revenues:
Net (loss) gain on natural gas, oil, and NGL derivatives	$ (9,663)	$ (22,860)	$ (96,737)	$ 141,588
Total revenues	360,962	265,498	939,094	922,455
Costs and expenses:
Lease operating expenses	22,325	20,020	64,143	60,044
Production taxes	9,348	5,419	23,861	14,464
Midstream gathering and processing	78,913	69,372	214,546	176,258
Depreciation, depletion and amortization	119,915	106,650	352,848	254,887
General and administrative	15,848	13,065	42,955	37,922
Accretion expense	1,037	456	3,056	1,148
Acquisition expense	0	33	0	2,391
Total costs and expenses	247,386	215,015	701,409	547,114
INCOME (LOSS) FROM OPERATIONS	113,576	50,483	237,685	375,341
OTHER (INCOME) EXPENSE:
Interest expense	33,253	27,130	100,922	74,797
Interest income	(92)	(37)	(162)	(927)
Litigation settlement	917	0	917	0
Insurance proceeds	0	0	(231)	0
Gain on sale of equity method investments	(2,733)	0	(124,768)	(12,523)
(Income) loss from equity method investments, net	(12,858)	2,737	(35,282)	33,468
Other income	(61)	(345)	(201)	(863)
Total other (income) expense	18,426	29,485	(58,805)	93,952
INCOME (LOSS) BEFORE INCOME TAXES	95,150	20,998	296,490	281,389
INCOME TAX EXPENSE (BENEFIT)	0	2,763	(69)	2,763
NET INCOME (LOSS)	$ 95,150	$ 18,235	$ 296,559	$ 278,626
NET INCOME PER COMMON SHARE:
Basic (in usd per share)	$ 0.55	$ 0.10	$ 1.69	$ 1.56
Diluted (in usd per share)	$ 0.55	$ 0.10	$ 1.68	$ 1.56
Weighted average common shares outstanding - Basic (in shares)	173,057,538	182,957,416	175,776,312	178,736,569
Weighted average common shares outstanding - Diluted (in shares)	173,304,914	183,008,436	176,440,461	179,130,570
Natural gas sales
Revenues:
Revenue from contract with customer	$ 271,167	$ 223,340	$ 753,261	$ 606,544
Oil and condensate sales
Revenues:
Revenue from contract with customer	45,682	31,459	140,687	85,338
Natural gas liquid sales
Revenues:
Revenue from contract with customer	$ 53,776	$ 33,559	$ 141,883	$ 88,985

CONSOLIDATED STATEMENTS OF COMP

CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (UNAUDITED) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Statement of Comprehensive Income [Abstract]
Net income	$ 95,150	$ 18,235	$ 296,559	$ 278,626
Foreign currency translation adjustment	3,052	6,832	(5,815)	12,719
Other comprehensive income (loss)	3,052	6,832	(5,815)	12,719
Comprehensive income	$ 98,202	$ 25,067	$ 290,744	$ 291,345

CONSOLIDATED STATEMENTS OF STOC

CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY (UNAUDITED) - USD ($) $ in Thousands	Total	Common Stock	Paid-in Capital	Accumulated Other Comprehensive (Loss) Income	Retained Deficit
Beginning balance (in shares) at Dec. 31, 2016		158,829,816
Beginning balance at Dec. 31, 2016	$ 2,183,892	$ 1,588	$ 3,946,442	$ (53,058)	$ (1,711,080)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	278,626				278,626
Other comprehensive income (loss)	12,719			12,719
Stock-based Compensation	7,988		7,988
Issuance of common stock for the Vitruvian Acquisition, net of related expenses (in shares)		23,852,117
Issuance of Common Stock for the Vitruvian Acquisition, net of related expenses	459,436	$ 239	459,197
Issuance of Restricted Stock (in shares)		399,843
Issuance of Restricted Stock	0	$ 4	(4)
Ending balance (in shares) at Sep. 30, 2017		183,081,776
Ending balance at Sep. 30, 2017	$ 2,942,661	$ 1,831	4,413,623	(40,339)	(1,432,454)
Beginning balance (in shares) at Dec. 31, 2017	183,105,910	183,105,910
Beginning balance at Dec. 31, 2017	$ 3,101,614	$ 1,831	4,416,250	(40,539)	(1,275,928)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	296,559				296,559
Other comprehensive income (loss)	(5,815)			(5,815)
Stock-based Compensation	9,654		9,654
Shares Repurchased (in shares)		(10,505,469)
Shares Repurchased	(109,997)	$ (105)	(109,892)
Issuance of Restricted Stock (in shares)		618,202
Issuance of Restricted Stock	$ 0	$ 6	(6)
Ending balance (in shares) at Sep. 30, 2018	173,218,643	173,218,643
Ending balance at Sep. 30, 2018	$ 3,292,015	$ 1,732	$ 4,316,006	$ (46,354)	$ (979,369)

CONSOLIDATED STATEMENTS OF CASH

CONSOLIDATED STATEMENTS OF CASH FLOWS (UNAUDITED) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017
Cash flows from operating activities:
Net income	$ 296,559	$ 278,626
Adjustments to reconcile net income to net cash provided by operating activities:
Accretion expense	3,056	1,148
Depletion, depreciation and amortization	352,848	254,887
Stock-based compensation expense	5,792	4,793
(Income) loss from equity investments	(35,040)	34,018
Change in fair value of derivative instruments	106,373	(129,692)
Deferred income tax benefit	(69)	0
Amortization of loan commitment fees	4,554	3,548
Gain on sale of equity method investments	(124,768)	(12,523)
Distributions from equity method investments	1,978	0
Changes in operating assets and liabilities:
Increase in accounts receivable—oil and natural gas sales	(10,618)	(20,056)
Increase in accounts receivable—joint interest and other	(2,277)	(23,289)
Increase in accounts receivable—related parties	(79)	(346)
Increase in prepaid expenses and other current assets	(4,830)	(2,531)
Decrease (increase) in other assets	1,228	(5,665)
Increase in accounts payable, accrued liabilities and other	14,968	111,335
Settlement of asset retirement obligation	(719)	(2,520)
Net cash provided by operating activities	608,956	491,733
Cash flows from investing activities:
Additions to other property and equipment	(7,134)	(16,288)
Acquisition of oil and natural gas properties	0	(1,339,456)
Additions to oil and natural gas properties	(755,263)	(789,743)
Proceeds from sale of oil and natural gas properties	4,820	4,079
Proceeds from sale of other property and equipment	217	658
Proceeds from sale of equity method investments	226,487	0
Contributions to equity method investments	(2,318)	(44,844)
Distributions from equity method investments	446	4,114
Net cash used in investing activities	(532,745)	(2,181,480)
Cash flows from financing activities:
Principal payments on borrowings	(165,428)	(183)
Borrowings on line of credit	225,000	365,000
Borrowings on term loan	0	2,951
Debt issuance costs and loan commitment fees	(772)	(8,261)
Payments on repurchase of stock	(109,997)	0
Proceeds from issuance of common stock, net of offering costs	0	(5,364)
Net cash (used in) provided by financing activities	(51,197)	354,143
Net increase (decrease) in cash, cash equivalents and restricted cash	25,014	(1,335,604)
Cash, cash equivalents and restricted cash at beginning of period	99,557	1,460,875
Cash, cash equivalents and restricted cash at end of period	124,571	125,271
Supplemental disclosure of cash flow information:
Interest payments	75,045	50,826
Income tax payments	0	0
Supplemental disclosure of non-cash transactions:
Capitalized stock-based compensation	3,862	3,195
Asset retirement obligation capitalized	1,094	11,557
Interest capitalized	3,956	8,753
Foreign currency translation (loss) gain on equity method investments	$ (5,815)	$ 12,719

NOTES TO CONSOLIDATED FINANCIAL

NOTES TO CONSOLIDATED FINANCIAL STATEMENTS	9 Months Ended
	Sep. 30, 2018
Organization, Consolidation and Presentation of Financial Statements [Abstract]
NOTES TO CONSOLIDATED FINANCIAL STATEMENTS	These consolidated financial statements have been prepared by Gulfport Energy Corporation (the “Company” or “Gulfport”) without audit, pursuant to the rules and regulations of the Securities and Exchange Commission (the “SEC”), and reflect all adjustments which, in the opinion of management, are necessary for a fair presentation of the results for the interim periods, on a basis consistent with the annual audited consolidated financial statements. All such adjustments are of a normal recurring nature. Certain information, accounting policies, and footnote disclosures normally included in financial statements prepared in accordance with generally accepted accounting principles ("GAAP") have been omitted pursuant to such rules and regulations, although the Company believes that the disclosures are adequate to make the information presented not misleading. These consolidated financial statements should be read in conjunction with the consolidated financial statements and the summary of significant accounting policies and notes thereto included in the Company’s most recent annual report on Form 10-K. Results for the three and nine month periods ended September 30, 2018 are not necessarily indicative of the results expected for the full year.

ACQUISITIONS

ACQUISITIONS	9 Months Ended
	Sep. 30, 2018
Business Combinations [Abstract]
ACQUISITIONS	ACQUISITIONS Vitruvian Acquisition In December 2016, the Company, through its wholly-owned subsidiary Gulfport MidCon LLC (“Gulfport MidCon”) (formerly known as SCOOP Acquisition Company, LLC), entered into an agreement to acquire certain assets of Vitruvian II Woodford, LLC (“Vitruvian”), an unrelated third-party seller (the “Vitruvian Acquisition”). The assets included in the Vitruvian Acquisition include 46,400 net surface acres located in Grady, Stephens and Garvin Counties, Oklahoma. On February 17, 2017, the Company completed the Vitruvian Acquisition for a total initial purchase price of approximately $1.85 billion , consisting of $1.35 billion in cash, subject to certain adjustments, and approximately 23.9 million shares of the Company’s common stock (of which approximately 5.2 million shares were placed in an indemnity escrow). The cash portion of the purchase price was funded with the net proceeds from the Company's December 2016 common stock and senior note offerings and cash on hand. Acquisition costs of $0.03 million and $2.4 million were incurred during the three and nine months ended September 30, 2017 , respectively, related to the Vitruvian Acquisition. No acquisition costs were incurred during the three and nine months ended September 30, 2018 . Allocation of Purchase Price The Vitruvian Acquisition qualified as a business combination for accounting purposes and, as such, the Company estimated the fair value of the acquired properties as of the February 17, 2017 acquisition date. The fair value of the assets acquired and liabilities assumed was estimated using assumptions that represent Level 3 inputs. See Note 11 for additional discussion of the measurement inputs. The Company estimated that the consideration paid in the Vitruvian Acquisition for these properties approximated the fair value that would be paid by a typical market participant. As a result, no goodwill or bargain purchase gain was recognized in conjunction with the purchase. The following table summarizes the consideration paid by the Company in the Vitruvian Acquisition to acquire the properties and the fair value amount of the assets acquired as of February 17, 2017. (In thousands) Consideration: Cash, net of purchase price adjustments $ 1,354,093 Fair value of Gulfport’s common stock issued 464,639 Total consideration $ 1,818,732 Estimated fair value of identifiable assets acquired and liabilities assumed: Oil and natural gas properties Proved properties $ 362,264 Unproved properties 1,462,957 Asset retirement obligations (6,489 ) Total fair value of net identifiable assets acquired $ 1,818,732 The equity consideration included in the initial purchase price was based on an equity offering price of $20.96 on December 15, 2016. The decrease in the price of Gulfport’s common stock from $20.96 on December 15, 2016 to $19.48 on February 17, 2017 resulted in a decrease to the fair value of the total consideration paid as compared to the initial purchase price of approximately $35.3 million , which resulted in a closing date fair value lower than the initial purchase price. Post-Acquisition Operating Results For the three months ended September 30, 2017 and the period from the acquisition date of February 17, 2017 to September 30, 2017 , the assets acquired in the Vitruvian Acquisition contributed the following amounts of revenue to the Company's consolidated statements of operations. The amount of net income contributed by the assets is not presented below as it is impracticable to calculate due to the Company integrating the acquired assets into its overall operations using the full cost method of accounting. Period from February 17, 2017 Three months ended to September 30, 2017 September 30, 2017 (In thousands) Revenue $ 60,940 $ 137,706 Pro Forma Information (Unaudited) The following unaudited pro forma combined financial information presents the Company’s results as though the Vitruvian Acquisition had been completed at January 1, 2017. The pro forma combined financial information has been included for comparative purposes and is not necessarily indicative of the results that might have actually occurred had the Vitruvian Acquisition taken place on January 1, 2017; furthermore, the financial information is not intended to be a projection of future results. Three months ended Nine months ended September 30, 2017 September 30, 2017 (In thousands, except share data) Pro forma revenue $ 265,498 $ 958,354 Pro forma net income $ 18,235 $ 300,052 Pro forma earnings per share (basic) $ 0.10 $ 1.68 Pro forma earnings per share (diluted) $ 0.10 $ 1.68

PROPERTY AND EQUIPMENT

PROPERTY AND EQUIPMENT	9 Months Ended
	Sep. 30, 2018
Property, Plant and Equipment [Abstract]
PROPERTY AND EQUIPMENT	PROPERTY AND EQUIPMENT The major categories of property and equipment and related accumulated depletion, depreciation, amortization and impairment as of September 30, 2018 and December 31, 2017 are as follows: September 30, 2018 December 31, 2017 (In thousands) Oil and natural gas properties $ 9,936,714 $ 9,169,156 Office furniture and fixtures 42,302 37,369 Building 44,565 44,565 Land 5,521 4,820 Total property and equipment 10,029,102 9,255,910 Accumulated depletion, depreciation, amortization and impairment (4,506,306 ) (4,153,733 ) Property and equipment, net $ 5,522,796 $ 5,102,177 Under the full cost method of accounting, the Company is required to perform a ceiling test each quarter. The test determines a limit, or ceiling, on the book value of the oil and natural gas properties. At September 30, 2018 , the calculated ceiling was greater than the net book value of the Company’s oil and natural gas properties, thus no ceiling test impairment was required for the nine months ended September 30, 2018 . No impairme nt was required for oil and natural gas properties for the nine months ended September 30, 2017 . Included in oil and natural gas properties at September 30, 2018 is the cumulative capitalization of $194.4 million in general and administrative costs incurred and capitalized to the full cost pool. General and administrative costs capitalized to the full cost pool represent management’s estimate of costs incurred directly related to exploration and development activities such as geological and other administrative costs associated with overseeing the exploration and development activities. All general and administrative costs not directly associated with exploration and development activities were charged to expense as they were incurred. Capitalized general and administrative costs were approximately $10.6 million and $28.8 million for the three and nine months ended September 30, 2018 , respectively, and $8.9 million and $25.6 million for the three and nine months ended September 30, 2017 , respectively. The average depletion rate per Mcfe, which is a function of capitalized costs, future development costs and the related underlying reserves in the periods presented, was $0.94 and $0.89 per Mcfe for the nine months ended September 30, 2018 and 2017 , respectively. The following table summarizes the Company’s non-producing properties excluded from amortization by area at September 30, 2018 : September 30, 2018 (In thousands) Utica $ 1,522,633 MidContinent 1,401,392 Niobrara 449 Southern Louisiana 571 Bakken 100 $ 2,925,145 At December 31, 2017 , approximately $2.9 billion of non-producing leasehold costs was not subject to amortization. The Company evaluates the costs excluded from its amortization calculation at least annually. Subject to industry conditions and the level of the Company’s activities, the inclusion of most of the above referenced costs into the Company’s amortization calculation typically occurs within three to five years. However, the majority of the Company’s non-producing leases in the Utica Shale have five -year extension terms which could extend this time frame beyond five years. A reconciliation of the Company’s asset retirement obligation for the nine months ended September 30, 2018 and 2017 is as follows: September 30, 2018 September 30, 2017 (In thousands) Asset retirement obligation, beginning of period $ 75,100 $ 34,276 Liabilities incurred 1,468 11,557 Liabilities settled (719 ) (2,520 ) Accretion expense 3,056 1,148 Revisions in estimated cash flows (374 ) — Asset retirement obligation as of end of period 78,531 44,461 Less current portion 120 195 Asset retirement obligation, long-term $ 78,411 $ 44,266

EQUITY INVESTMENTS

EQUITY INVESTMENTS	9 Months Ended
	Sep. 30, 2018
Equity Method Investments and Joint Ventures [Abstract]
EQUITY INVESTMENTS	EQUITY INVESTMENTS Investments accounted for by the equity method consist of the following as of September 30, 2018 and December 31, 2017 : Carrying value (Income) loss from equity method investments Approximate ownership % September 30, 2018 December 31, 2017 Three months ended September 30, Nine months ended September 30, 2018 2017 2018 2017 (In thousands) Investment in Tatex Thailand II, LLC 23.5 % $ — $ — $ (137 ) $ (95 ) $ (241 ) $ (549 ) Investment in Grizzly Oil Sands ULC 24.9999 % 53,381 57,641 275 296 833 869 Investment in Timber Wolf Terminals LLC 50.0 % — 983 — 4 536 8 Investment in Windsor Midstream LLC 22.5 % 39 30 — (2 ) (9 ) 25,232 Investment in Stingray Cementing LLC (1) — % — — — — — 205 Investment in Stingray Energy Services LLC (1) — % — — — — — 282 Investment in Sturgeon Acquisitions LLC (1) — % — — — — — (71 ) Investment in Mammoth Energy Services, Inc. (1) 22.0 % 179,109 165,715 (12,996 ) 2,407 (35,708 ) 4,907 Investment in Strike Force Midstream LLC (2) — % — 77,743 — 127 (693 ) 2,585 $ 232,529 $ 302,112 $ (12,858 ) $ 2,737 $ (35,282 ) $ 33,468 (1) On June 5, 2017, Mammoth Energy Services, Inc. ("Mammoth Energy") acquired Stingray Cementing LLC, Stingray Energy Services LLC and Sturgeon Acquisitions LLC. See below under Mammoth Energy Partners LP/Mammoth Energy Services, Inc. for information regarding these transactions. (2) On May 1, 2018, the Company sold its 25% interest in Strike Force Midstream to EQT Midstream Partners, LP. See below under under Strike Force Midstream LLC for information regarding this transaction. The tables below summarize financial information for the Company’s equity investments as of September 30, 2018 and December 31, 2017 . Summarized balance sheet information: September 30, 2018 December 31, 2017 (In thousands) Current assets $ 481,394 $ 415,032 Noncurrent assets $ 1,336,604 $ 1,542,090 Current liabilities $ 358,177 $ 261,086 Noncurrent liabilities $ 48,328 $ 148,839 Summarized results of operations: Three months ended September 30, Nine months ended September 30, 2018 2017 2018 2017 (In thousands) Gross revenue $ 384,043 $ 160,950 $ 1,451,580 $ 357,901 Net income (loss) $ 68,414 $ 2,101 $ 181,884 $ (109,651 ) Tatex Thailand II, LLC The Company has an indirect ownership interest in Tatex Thailand II, LLC (“Tatex II”). Tatex II holds an 8.5% interest in APICO, LLC (“APICO”), an international oil and gas exploration company. APICO has a reserve base located in Southeast Asia through its ownership of concessions covering approximately 180,000 acres which includes the Phu Horm Field. The Company received $0.2 million and $0.5 million in distributions from Tatex II during the nine months ended September 30, 2018 and 2017 , respectively. Tatex Thailand III, LLC The Company has an ownership interest in Tatex Thailand III, LLC (“Tatex III”). Tatex III previously owned a concession covering approximately 245,000 acres in Southeast Asia. As of December 31, 2014, the Company reviewed its investment in Tatex III and, together with Tatex III, made the decision to allow the concession to expire in January 2015. As such, the Company fully impaired the asset as of December 31, 2014. In December 2017, Tatex III was dissolved and the Company received a final distribution of $0.2 million . Grizzly Oil Sands ULC The Company, through its wholly owned subsidiary Grizzly Holdings Inc. (“Grizzly Holdings”), owns an interest in Grizzly Oil Sands ULC (“Grizzly”), a Canadian unlimited liability company. The remaining interest in Grizzly is owned by Grizzly Oil Sands Inc. (“Oil Sands”). As of September 30, 2018 , Grizzly had approximately 830,000 acres under lease in the Athabasca, Peace River and Cold Lake oil sands regions of Alberta, Canada. Grizzly has high-graded three oil sands projects to various stages of development. Grizzly commenced commercial production from its Algar Lake Phase I steam-assisted gravity drainage ("SAGD") oil sand project during the second quarter of 2014 and has regulatory approval for up to 11,300 barrels per day of bitumen production. Algar Lake production peaked at 2,200 barrels per day during the ramp-up phase of the SAGD facility, however, in April 2015, Grizzly made the decision to suspend operations at its Algar Lake facility due to the commodity price drop and its effect on project economics. Grizzly continues to monitor market conditions as it assesses start up plans for the facility. The Company reviewed its investment in Grizzly for impairment at September 30, 2018 and 2017 and determined no impairment was required. If commodity prices decline in the future however, impairment of the investment in Grizzly may be necessary. During the nine months ended September 30, 2018 , Gulfport paid $2.3 million in cash calls. Grizzly’s functional currency is the Canadian dollar. The Company’s investment in Grizzly was increased by a $2.9 million foreign currency translation gain and decreased by a $5.7 million foreign currency translation loss for the three and nine months ended September 30, 2018 , respectively. The Company’s investment in Grizzly was increased by $6.7 million and $12.5 million as a result of a foreign currency translation gain for the three and nine months ended September 30, 2017, respectively. Timber Wolf Terminals LLC During 2012, the Company invested in Timber Wolf Terminals LLC (“Timber Wolf”). Timber Wolf was formed to operate a crude/condensate terminal and a sand transloading facility in Ohio. During the nine months ended September 30, 2018 and 2017 , the Company paid no cash calls to Timber Wolf. The Company received $0.4 million in distributions from Timber Wolf during the nine months ended September 30, 2018 resulting from the sale of assets held by Timber Wolf. Windsor Midstream LLC At September 30, 2018 , the Company held a 22.5% interest in Windsor Midstream LLC (“Midstream”), an entity controlled and managed by an unrelated third party. The Company received no distributions from Midstream during the nine months ended September 30, 2018 and $0.5 million in distributions during the same period in 2017 . Stingray Cementing LLC During 2012, the Company invested in Stingray Cementing LLC (“Stingray Cementing”). Stingray Cementing provides well cementing services. The (income) loss from equity method investments presented in the table above reflects any intercompany profit eliminations. On June 5, 2017 , the Company contributed all of its membership interests in Stingray Cementing to Mammoth Energy. See below under Mammoth Energy Partners LP/Mammoth Energy Services, Inc. for information regarding this transaction. Stingray Energy Services LLC During 2013, the Company invested in Stingray Energy Services LLC (“Stingray Energy”). Stingray Energy provides rental tools for land-based oil and natural gas drilling, completion and workover activities as well as the transfer of fresh water to wellsites. The (income) loss from equity method investments presented in the table above reflects any intercompany profit eliminations. On June 5, 2017 , the Company contributed all of its membership interests in Stingray Energy to Mammoth Energy. See below under Mammoth Energy Partners LP/Mammoth Energy Services, Inc. for information regarding this transaction. Sturgeon Acquisitions LLC During 2014, the Company invested in Sturgeon Acquisitions LLC (“Sturgeon”) and received an ownership interest of 25% in Sturgeon. Sturgeon owns and operates sand mines that produce hydraulic fracturing grade sand. On June 5, 2017 , the Company contributed all of its membership interests in Sturgeon to Mammoth Energy. See below under Mammoth Energy Partners LP/Mammoth Energy Services, Inc. for information regarding this transaction. Mammoth Energy Partners LP/Mammoth Energy Services, Inc. In the fourth quarter of 2014, the Company contributed its investments in four entities to Mammoth Energy Partners LP (“Mammoth”) for a 30.5% interest in this entity. In October 2016, Mammoth converted from a limited partnership into a limited liability company named Mammoth Energy Partners LLC (“Mammoth LLC”) and the Company and the other members of Mammoth LLC contributed their interests in Mammoth LLC to Mammoth Energy. Following the contribution, Mammoth Energy completed its initial public offering of shares of its common stock. On June 5, 2017 , the Company contributed all of its membership interests in Sturgeon (which owned Taylor Frac, LLC, Taylor Real Estate Investments, LLC and South River Road, LLC), Stingray Energy and Stingray Cementing to Mammoth Energy in exchange for approximately 2.0 million shares of Mammoth Energy common stock (the "June 2017 Transactions"). The Company accounted for the transactions as a sale of financial assets under ASC 860, Transfers and Servicing . The Company valued the shares of Mammoth Energy common stock it received in the June 2017 Transactions at $18.50 per share, which was the closing price of Mammoth Energy common stock on June 5, 2017 . During the second quarter of 2017, the Company recognized a gain of $12.5 million from the June 2017 Transactions, which is included in gain on sale of equity method investments in the accompanying consolidated statement of operations. On June 29, 2018, the Company sold 1,235,600 shares of its Mammoth Energy common stock in an underwritten public offering for net proceeds of approximately $47.0 million . In connection with the Company's public offering of a portion of its shares of Mammoth Energy common stock, the Company granted the underwriters an option to purchase additional shares of its Mammoth Energy common stock. On July 26, 2018, the underwriters exercised this option, in part, and on July 30, 2018, the Company sold an additional 118,974 shares for net proceeds of approximately $4.5 million . Following the sales of these shares, the Company owned 9,829,548 shares, or approximately 22.0% , of Mammoth Energy's outstanding common stock. As a result of the sales, the Company recorded a gain of $2.7 million and $28.3 million for the three and nine months ended September 30, 2018 , which is included in gain on sale of equity method investments in the accompanying consolidated statements of operations. The Company’s investment in Mammoth Energy was increased by a $0.1 million foreign currency gain and decreased by a $0.2 million foreign currency loss resulting from Mammoth Energy’s foreign subsidiary for the three and nine months ended September 30, 2018 , respectively. The Company’s investment in Mammoth Energy was increased by a $0.16 million and $0.2 million foreign currency gain resulting from Mammoth Energy’s foreign subsidiary for the three and nine months ended September 30, 2017 , respectively. During the nine months ended September 30, 2018 , Gulfport received distributions of $1.2 million from Mammoth Energy as a result of a $0.125 per share dividend in August 2018. The (income) loss from equity method investments presented in the table above reflects any intercompany profit eliminations. Strike Force Midstream LLC In February 2016, the Company, through its wholly-owned subsidiary Gulfport Midstream Holdings, LLC (“Midstream Holdings”), entered into an agreement with Rice Midstream Holdings LLC (“Rice”), then a subsidiary of Rice Energy Inc., to develop natural gas gathering assets in eastern Belmont County and Monroe County, Ohio through Strike Force Midstream LLC ("Strike Force"). In 2017, Rice was acquired by EQT Corporation ("EQT"). Prior to the sale of the Company's interest in Strike Force (discussed below), the Company owned a 25% interest in Strike Force, and EQT acted as operator and owned the remaining 75% interest. Strike Force's gathering assets provide gathering services for wells operated by Gulfport and other operators and connectivity of existing dry gas gathering systems. Prior to the sale of its interest in Strike Force, the Company elected to report its proportionate share of Strike Force’s earnings on a one-quarter lag as permitted under ASC 323, Investments - Equity Method and Joint Ventures . The (income) loss from equity method investments presented in the table above reflects any intercompany profit eliminations. During the nine months ended September 30, 2018 , Gulfport received distributions of $0.8 million from Strike Force. During the nine months ended September 30, 2017 , Gulfport paid $43.0 million in cash calls to Strike Force and received distributions of $3.6 million from Strike Force. On May 1, 2018, the Company sold its 25% interest in Strike Force to EQT Midstream Partners, LP for proceeds of $175.0 million in cash. As a result of the sale, the Company recognized a gain of $96.4 million net of transaction fees, which is included in gain on sale of equity method investments in the accompanying consolidated statement of operations.

VARIABLE INTEREST ENTITIES

VARIABLE INTEREST ENTITIES	9 Months Ended
	Sep. 30, 2018
Related Party Transactions [Abstract]
VARIABLE INTEREST ENTITIES	VARIABLE INTEREST ENTITIES As of September 30, 2018 , the Company held variable interests in the following variable interest entities (“VIEs”), but was not the primary beneficiary: Midstream and Timber Wolf. These entities have governing provisions that are the functional equivalent of a limited partnership and are considered VIEs because the limited partners or non-managing members lack substantive kick-out or participating rights which causes the equity owners, as a group, to lack a controlling financial interest. The Company is a limited partner or non-managing member in each of these VIEs and is not the primary beneficiary because it does not have a controlling financial interest. The general partner or managing member has power to direct the activities that most significantly impact the VIEs’ economic performance. The Company also held a variable interest in Strike Force prior to the sale of that interest due to the fact that it did not have sufficient equity capital at risk. The Company was not the primary beneficiary of this entity. Prior to Mammoth Energy’s initial public offering, or "IPO", Mammoth LLC was considered a VIE. As a result of the Company’s contribution of its interest in Mammoth LLC to Mammoth Energy in exchange for Mammoth Energy common stock and the completion of Mammoth Energy’s IPO, the Company determined that it no longer held an interest in a VIE. Prior to the contribution of Stingray Energy, Stingray Cementing and Sturgeon to Mammoth Energy, these entities were considered VIEs. As a result of the Company’s contribution of its membership interests in Stingray Energy, Stingray Cementing and Sturgeon to Mammoth Energy in exchange for Mammoth Energy common stock, the Company determined that it no longer held an interest in a VIE. The Company accounts for its investment in these VIEs following the equity method of accounting. The carrying amounts of the Company’s equity investments are classified as other non-current assets on the accompanying consolidated balance sheets. The Company’s maximum exposure to loss as a result of its involvement with these VIEs is based on the Company’s capital contributions and the economic performance of the VIEs, and is equal to the carrying value of the Company’s investments which is the maximum loss the Company could be required to record in the consolidated statements of operations. See Note 3 for further discussion of these entities, including the carrying amounts of each investment.

LONG-TERM DEBT

LONG-TERM DEBT	9 Months Ended
	Sep. 30, 2018
Long-term Debt, Unclassified [Abstract]
LONG-TERM DEBT	LONG-TERM DEBT Long-term debt consisted of the following items as of September 30, 2018 and December 31, 2017 : September 30, 2018 December 31, 2017 (In thousands) Revolving credit agreement (1) $ 60,000 $ — 6.625% senior unsecured notes due 2023 (2) 350,000 350,000 6.000% senior unsecured notes due 2024 (3) 650,000 650,000 6.375% senior unsecured notes due 2025 (4) 600,000 600,000 6.375% senior unsecured notes due 2026 (5) 450,000 450,000 Net unamortized debt issuance costs (6) (31,824 ) (34,781 ) Construction loan (7) 23,296 23,724 Less: current maturities of long term debt (647 ) (622 ) Debt reflected as long term $ 2,100,825 $ 2,038,321 The Company capitalized approximately $1.6 million and $4.0 million in interest expense to undeveloped oil and natural gas properties during the three and nine months ended September 30, 2018 , respectively. The Company capitalized approximately $2.1 million and $8.8 million in interest expense to undeveloped oil and natural gas properties during the three and nine months ended September 30, 2017 , respectively. (1) The Company has entered into a senior secured revolving credit facility, as amended, with The Bank of Nova Scotia, as the lead arranger and administrative agent and certain lenders from time to time party thereto. The credit agreement provides for a maximum facility amount of $1.5 billion and matures on December 31, 2021. On March 29, 2017, the Company further amended its revolving credit facility to, among other things, amend the definition of the term EBITDAX to permit pro forma treatment of acquisitions that involve the payment of consideration by Gulfport and its subsidiaries in excess of $50.0 million and of dispositions of property or series of related dispositions of properties that yields gross proceeds to Gulfport or any of its subsidiaries in excess of $50.0 million . On May 4, 2017, the revolving credit facility was further amended to increase the borrowing base from $700.0 million to $1.0 billion , adjust certain of the Company’s investment baskets and add five additional banks to the syndicate. On November 21, 2017, the Company further amended its revolving credit facility to, among other things, (a) decrease the applicable rate for all loans by 0.5% and (b) add a provision that allows Gulfport to elect a commitment amount (the “Elected Commitment Amount”) that is less than the borrowing base. In connection with this amendment, the borrowing base was set at $1.2 billion , with an elected commitment of $1.0 billion . On May 21, 2018, the Company further amended its revolving credit facility to, among other things, (a) decrease the applicable rate for all loans by 0.25% , (b) permit Gulfport and each of its subsidiaries to use the proceeds from dispositions of certain investments to acquire the common stock or other equity interests of Gulfport, subject to certain limitations and (c) increase the borrowing base to $1.4 billion , with an elected commitment of $1.0 billion . As of September 30, 2018 , $60.0 million was outstanding under the revolving credit facility and the total availability for future borrowings under this facility, after giving effect to an aggregate of $316.2 million of letters of credit, was $623.8 million . The Company’s wholly-owned subsidiaries have guaranteed the obligations of the Company under the revolving credit facility. Advances under the revolving credit facility may be in the form of either base rate loans or eurodollar loans. The interest rate for base rate loans is equal to (1) the applicable rate, which ranges from 0.25% to 1.25% , plus (2) the highest of: (a) the federal funds rate plus 0.50% , (b) the rate of interest in effect for such day as publicly announced from time to time by agent as its “prime rate,” and (c) the eurodollar rate for an interest period of one month plus 1.00% . The interest rate for eurodollar loans is equal to (1) the applicable rate, which ranges from 1.25% to 2.25% , plus (2) the London interbank offered rate that appears on pages LIBOR01 or LIBOR02 of the Reuters screen that displays such rate for deposits in U.S. dollars, or, if such rate is not available, the rate as administered by ICE Benchmark Administration (or any other person that takes over administration of such rate) per annum equal to the offered rate on such other page or service that displays on average London interbank offered rate as determined by ICE Benchmark Administration (or any other person that takes over administration of such rate) for deposits in U.S. dollars, or, if such rate is not available, the average quotations for three major New York money center banks of whom the agent shall inquire as the “London Interbank Offered Rate” for deposits in U.S. dollars. At September 30, 2018 , amounts borrowed under the credit facility bore interest at the eurodollar rate with a weighted average of 3.72% . The revolving credit facility contains customary negative covenants including, but not limited to, restrictions on the Company’s and its subsidiaries’ ability to: • incur indebtedness; • grant liens; • pay dividends and make other restricted payments; • make investments; • make fundamental changes; • enter into swap contracts; • dispose of assets; • change the nature of their business; and • enter into transactions with affiliates. The negative covenants are subject to certain exceptions as specified in the revolving credit facility. The revolving credit facility also contains certain affirmative covenants, including, but not limited to the following financial covenants: (i) the ratio of net funded debt to EBITDAX (net income, excluding (i) any non-cash revenue or expense associated with swap contracts resulting from ASC 815 and (ii) any cash or non-cash revenue or expense attributable to minority investments plus without duplication and, in the case of expenses, to the extent deducted from revenues in determining net income, the sum of (a) the aggregate amount of consolidated interest expense for such period, (b) the aggregate amount of income, franchise, capital or similar tax expense (other than ad valorem taxes) for such period, (c) all amounts attributable to depletion, depreciation, amortization and asset or goodwill impairment or writedown for such period, (d) all other non-cash charges, (e) exploration costs deducted in determining net income under successful efforts accounting, (f) actual cash distributions received from minority investments, (g) to the extent actually reimbursed by insurance, expenses with respect to liability on casualty events or business interruption, and (h) all reasonable transaction expenses related to dispositions and acquisitions of assets, investments and debt and equity offerings (provided that expenses related to any unsuccessful disposition will be limited to $3.0 million in the aggregate) for a twelve-month period may not be greater than 4.00 to 1.00 ; and (ii) the ratio of EBITDAX to interest expense for a twelve-month period may not be less than 3.00 to 1.00 . The Company was in compliance with its financial covenants at September 30, 2018 . (2) On April 21, 2015, the Company issued $350.0 million in aggregate principal amount of 6.625% Senior Notes due 2023 (the “2023 Notes”) to qualified institutional buyers pursuant to Rule 144A under the Securities Act and to certain non-U.S. persons in accordance with Regulation S under the Securities Act (the “2023 Notes Offering”). The Company received net proceeds of approximately $343.6 million after initial purchaser discounts and commissions and estimated offering expenses. The 2023 Notes were issued under an indenture, dated as of April 21, 2015, among the Company, the subsidiary guarantors party thereto and Wells Fargo Bank, National Association, as trustee. In October 2015, the 2023 Notes were exchanged for a new issue of substantially identical debt securities registered under the Securities Act. Pursuant to the indenture relating to the 2023 Notes, interest on the 2023 Notes accrues at a rate of 6.625% per annum on the outstanding principal amount thereof, payable semi-annually on May 1 and November 1 of each year. The 2023 Notes are not guaranteed by Grizzly Holdings, Inc. and will not be guaranteed by any of the Company’s future unrestricted subsidiaries. (3) On October 14, 2016, the Company issued $650.0 million in aggregate principal amount of 6.000% Senior Notes due 2014 (the "2024 Notes"). The 2024 Notes were issued under an indenture, dated as of October 14, 2016, among the Company, the subsidiary guarantors party thereto and the senior note indenture trustee (the “2024 Indenture”), to qualified institutional buyers pursuant to Rule 144A under the Securities Act and to certain non-U.S. persons in accordance with Regulation S under the Securities Act (the “2024 Notes Offering”). Under the 2024 Indenture, interest on the 2024 Notes accrues at a rate of 6.000% per annum on the outstanding principal amount thereof from October 14, 2016, payable semi-annually on April 15 and October 15 of each year, commencing on April 15, 2017. The 2024 Notes will mature on October 15, 2024. The Company received approximately $638.9 million in net proceeds from the offering of the 2024 Notes, which was used, together with cash on hand, to purchase the then outstanding 2020 Notes in a concurrent cash tender offer, to pay fees and expenses thereof, and to redeem any of the 2020 Notes that remained outstanding after the completion of the tender offer. (4) On December 21, 2016, the Company issued $600.0 million in aggregate principal amount of 6.375% Senior Notes due 2025 (the “2025 Notes”). The 2025 Notes were issued under an indenture, dated as of December 21, 2016, among the Company, the subsidiary guarantors party thereto and the senior note indenture trustee (the “2025 Indenture”), to qualified institutional buyers pursuant to Rule 144A under the Securities Act of 1933, and to certain non-U.S. persons in accordance with Regulation S under the Securities Act. Under the 2025 Indenture, interest on the 2025 Notes accrues at a rate of 6.375% per annum on the outstanding principal amount thereof from December 21, 2016, payable semi-annually on May 15 and November 15 of each year, commencing on May 15, 2017. The 2025 Notes will mature on May 15, 2025. The Company received approximately $584.7 million in net proceeds from the offering of the 2025 Notes, which was used, together with the net proceeds from the Company’s December 2016 common stock offering and cash on hand, to fund the cash portion of the purchase price for the Vitruvian Acquisition. See “Note 1 – Acquisitions” for additional discussion of the Vitruvian Acquisition. (5) On October 11, 2017, the Company issued $450.0 million in aggregate principal amount of its 6.375% Senior Notes due 2026 (the “2026 Notes”) to qualified institutional buyers pursuant to Rule 144A under the Securities Act and to certain non-U.S. persons in accordance with Regulation S under the Securities Act. Interest on the 2026 Notes accrues at a rate of 6.375% per annum on the outstanding principal amount thereof from October 11, 2017, payable semi-annually on January 15 and July 15 of each year, commencing on January 15, 2018. The 2026 Notes will mature on January 15, 2026. The Company received approximately $444.1 million in net proceeds from the offering of the 2026 Notes, a portion of which was used to repay all of the Company's outstanding borrowings under its secured revolving credit facility on October 11, 2017 and the balance was used to fund the remaining outspend related to the Company's 2017 capital development plans. In connection with the 2026 Notes offering, the Company and its subsidiary guarantors entered into a registration rights agreement pursuant to which the Company agreed to file a registration statement with respect to an offer to exchange the 2026 Notes for a new issue of substantially identical debt securities registered under the Securities Act. On January 18, 2018, the Company filed a registration statement on Form S-4 with respect to an offer to exchange the 2026 Notes for substantially identical debt securities registered under the Securities Act, which registration statement was declared effective by the SEC on February 12, 2018. The exchange offer relating to the 2026 notes closed on March 22, 2018. (6) Loan issuance costs related to the 2023 Notes, the 2024 Notes, the 2025 Notes and the 2026 Notes (collectively the “Notes”) have been presented as a reduction to the Notes. At September 30, 2018 , total unamortized debt issuance costs were $4.6 million for the 2023 Notes, $9.0 million for the 2024 Notes, $12.9 million for the 2025 Notes and $5.2 million for the 2026 Notes. In addition, loan commitment fee costs for the construction loan agreement described immediately below were $0.1 million at September 30, 2018 . (7) On June 4, 2015, the Company entered into a construction loan agreement (the “Construction Loan”) with InterBank for the construction of a new corporate headquarters in Oklahoma City, which was substantially completed in December 2016. The Construction Loan allows for maximum principal borrowings of $24.5 million and required the Company to fund 30% of the cost of the construction before any funds could be drawn, which occurred in January 2016. Interest accrues daily on the outstanding principal balance at a fixed rate of 4.50% per annum and was payable on the last day of the month through May 31, 2017. Starting June 30, 2017, the Company began making monthly payments of principal and interest, with the final payment due June 4, 2025. At September 30, 2018 , the total borrowings under the Construction Loan were approximately $23.3 million .

COMMON STOCK AND CHANGES IN CAP

COMMON STOCK AND CHANGES IN CAPITALIZATION	9 Months Ended
	Sep. 30, 2018
Equity [Abstract]
COMMON STOCK AND CHANGES IN CAPITALIZATION	COMMON STOCK AND CHANGES IN CAPITALIZATION Issuance of Common Stock On February 17, 2017, the Company completed the Vitruvian Acquisition for a total initial purchase price of approximately $1.85 billion , consisting of $1.35 billion in cash, subject to certain adjustments, and approximately 23.9 million shares of the Company’s common stock (of which approximately 5.2 million shares are subject to the indemnity escrow). See “Note 1 - Acquisitions” for additional discussion of the Vitruvian Acquisition. Stock Repurchase Program In January 2018, the board of directors of the Company approved a stock repurchase program to acquire up to $100 million of the Company's outstanding stock during 2018. In May 2018, the Company's board of directors authorized the expansion of its stock repurchase program, authorizing the Company to acquire up to an additional $100 million of its outstanding common stock during 2018 for a total of up to $200 million . Purchases under the repurchase program may be made from time to time in open market or privately negotiated transactions, and are subject to market conditions, applicable legal requirements, contractual obligations and other factors. The repurchase program does not require the Company to acquire any specific number of shares. This repurchase program is authorized to extend through December 31, 2018 and may be suspended from time to time, modified, extended or discontinued by the board of directors at any time. The Company repurchased 0.4 million and 10.5 million shares for a cost of approximately $5.0 million and $110.0 million during the three and nine months ended September 30, 2018 , respectively. All repurchased shares have been retired.

STOCK-BASED COMPENSATION

STOCK-BASED COMPENSATION	9 Months Ended
	Sep. 30, 2018
Share-based Compensation [Abstract]
STOCK-BASED COMPENSATION	STOCK-BASED COMPENSATION During the three and nine months ended September 30, 2018 , the Company’s stock-based compensation cost was $3.6 million and $9.7 million , respectively, of which the Company capitalized $1.4 million and $3.9 million , respectively, relating to its exploration and development efforts. During the three and nine months ended September 30, 2017 , the Company’s stock-based compensation cost was $2.8 million and $8.0 million , respectively, of which the Company capitalized $1.1 million and $3.2 million , respectively, relating to its exploration and development efforts. The following table summarizes restricted stock activity for the nine months ended September 30, 2018 : Number of Unvested Restricted Shares Weighted Average Grant Date Fair Value Unvested shares as of January 1, 2018 976,027 $ 18.71 Granted 1,197,628 9.45 Vested (618,202 ) 17.77 Forfeited (32,633 ) 17.31 Unvested shares as of September 30, 2018 1,522,820 $ 11.84 Unrecognized compensation expense as of September 30, 2018 related to restricted shares was $15.5 million . The expense is expected to be recognized over a weighted average period of 1.63 years.

EARNINGS PER SHARE

EARNINGS PER SHARE	9 Months Ended
	Sep. 30, 2018
Earnings Per Share [Abstract]
EARNINGS PER SHARE	EARNINGS PER SHARE Reconciliations of the components of basic and diluted net income per common share are presented in the tables below: Three months ended September 30, 2018 2017 Income Shares Per Share Income Shares Per Share (In thousands, except share data) Basic: Net income $ 95,150 173,057,538 $ 0.55 $ 18,235 182,957,416 $ 0.10 Effect of dilutive securities: Stock options and awards — 247,376 — 51,020 Diluted: Net income $ 95,150 173,304,914 $ 0.55 $ 18,235 183,008,436 $ 0.10 Nine months ended September 30, 2018 2017 Income Shares Per Income Shares Per (In thousands, except share data) Basic: Net income $ 296,559 175,776,312 $ 1.69 $ 278,626 178,736,569 $ 1.56 Effect of dilutive securities: Stock options and awards — 664,149 — 394,001 Diluted: Net income $ 296,559 176,440,461 $ 1.68 $ 278,626 179,130,570 $ 1.56

COMMITTMENTS AND CONTINGENCIES

COMMITTMENTS AND CONTINGENCIES	9 Months Ended
	Sep. 30, 2018
Commitments and Contingencies Disclosure [Abstract]
COMMITMENTS AND CONTINGENCIES	COMMITMENTS AND CONTINGENCIES Plugging and Abandonment Funds In connection with the Company’s acquisition in 1997 of the remaining 50% interest in its WCBB properties, the Company assumed the seller’s (Chevron) obligation to contribute approximately $18,000 per month through March 2004 to a plugging and abandonment trust and the obligation to plug a minimum of 20 wells per year for 20 years commencing March 11, 1997. Beginning in 2009, the Company could access the trust for use in plugging and abandonment charges associated with the property, although it has not yet done so. As of September 30, 2018 , the plugging and abandonment trust totaled approximately $3.1 million . At September 30, 2018 , the Company had plugged 555 wells at WCBB since it began its plugging program in 1997, which management believes fulfills its minimum plugging obligation. Operating Leases The Company leases office facilities under non-cancellable operating leases exceeding one year . Future minimum lease commitments under these leases at September 30, 2018 were as follows: (In thousands) Remaining 2018 $ 39 2019 144 2020 90 2021 38 Total $ 311 Firm Transportation and Sales Commitments The Company had approximately 2,659,000 MMBtu per day of firm sales contracted with third parties. The table below presents these commitments at September 30, 2018 as follows: (MMBtu per day) Remaining 2018 590,000 2019 659,000 2020 526,000 2021 372,000 2022 272,000 Thereafter 240,000 Total 2,659,000 The Company also had approximately $3.6 billion of firm transportation contracted with third parties. The table below presents these commitments at September 30, 2018 as follows: (In thousands) Remaining 2018 $ 62,012 2019 251,644 2020 247,581 2021 246,620 2022 246,620 Thereafter 2,511,853 Total $ 3,566,330 Other Commitments Effective October 1, 2014, the Company entered into a Sand Supply Agreement with Muskie Proppant LLC (“Muskie”), a subsidiary of Mammoth Energy. Effective August 3, 2018, the Company extended the agreement through December 31, 2021. Pursuant to this agreement, as amended, the Company has agreed to purchase annual and monthly amounts of proppant sand subject to exceptions specified in the agreement at agreed pricing plus agreed costs and expenses. Failure by either Muskie or the Company to deliver or accept the minimum monthly amount results in damages calculated per ton based on the difference between the monthly obligation amount and the amount actually delivered or accepted, as applicable. The Company incurred $1.3 million and $1.5 million in non-utilization fees under this agreement during the three and nine months ended September 30, 2018 , respectively. The Company did not incur any non-utilization fees during the nine months ended September 30, 2017 . Effective October 1, 2014, the Company entered into an Amended and Restated Master Services Agreement for pressure pumping services with Stingray Pressure Pumping LLC (“Stingray Pressure”), a subsidiary of Mammoth Energy. Pursuant to this agreement, as amended effective July 1, 2018, Stingray Pressure has agreed to provide hydraulic fracturing, stimulation and related completion and rework services to the Company and the Company has agreed to pay Stingray Pressure a monthly service fee plus the associated costs of the services provided. The Company has the right to suspend services of one crew and only one crew at any point in time without payment, fee or other obligation associated with the suspended crew, given appropriate notification of suspension. Future minimum commitments under these agreements at September 30, 2018 are $154.2 million . Litigation In two separate complaints, one filed by the State of Louisiana and the Parish of Cameron in the 38th Judicial District Court for the Parish of Cameron on February 9, 2016 and the other filed by the State of Louisiana and the District Attorney for the 15 th Judicial District of the State of Louisiana in the 15 th Judicial District Court for the Parish of Vermilion on July 29, 2016, the Company was named as a defendant, among 26 oil and gas companies, in the Cameron Parish complaint and among more than 40 oil and gas companies in the Vermilion Parish complaint, or the Complaints. The Complaints were filed under the State and Local Coastal Resources Management Act of 1978, as amended, and the rules, regulations, orders and ordinances adopted thereunder, which the Company referred to collectively as the CZM Laws, and allege that certain of the defendants’ oil and gas exploration, production and transportation operations associated with the development of the East Hackberry and West Hackberry oil and gas fields, in the case of the Cameron Parish complaint, and the Tigre Lagoon and Lac Blanc oil and gas fields, in the case of the Vermilion Parish complaint, were conducted in violation of the CZM Laws. The Complaints allege that such activities caused substantial damage to land and waterbodies located in the coastal zone of the relevant Parish, including due to defendants’ design, construction and use of waste pits and the alleged failure to properly close the waste pits and to clear, re-vegetate, detoxify and return the property affected to its original condition, as well as the defendants’ alleged discharge of waste into the coastal zone. The Complaints also allege that the defendants’ oil and gas activities have resulted in the dredging of numerous canals, which had a direct and significant impact on the state coastal waters within the relevant Parish and that the defendants, among other things, failed to design, construct and maintain these canals using the best practical techniques to prevent bank slumping, erosion and saltwater intrusion and to minimize the potential for inland movement of storm-generated surges, which activities allegedly have resulted in the erosion of marshes and the degradation of terrestrial and aquatic life therein. The Complaints also allege that the defendants failed to re-vegetate, refill, clean, detoxify and otherwise restore these canals to their original condition. In these two petitions, the plaintiffs seek damages and other appropriate relief under the CZM Laws, including the payment of costs necessary to clear, re-vegetate, detoxify and otherwise restore the affected coastal zone of the relevant Parish to its original condition, actual restoration of such coastal zone to its original condition, and the payment of reasonable attorney fees and legal expenses and pre-judgment and post judgment interest. The Company was served with the Cameron complaint in early May 2016 and with the Vermilion complaint in early September 2016. The Louisiana Attorney General and the Louisiana Department of Natural Resources intervened in both the Cameron Parish suit and the Vermilion Parish suit. Shortly after the Complaints were filed, certain defendants removed the cases to the United States District Court for the Western District of Louisiana. In both cases, the plaintiffs filed motions to remand the lawsuits to state court, which were ultimately granted by the district courts. However, on May 23, 2018, a group of defendants again removed the Cameron Parish and Vermilion Parish lawsuits to federal court. In response, the plaintiffs again filed motions to remand the cases to state court. The removing defendants have opposed plaintiffs’ motions to remand. The motions to remand remain pending, and further action in the cases will be stayed until the courts rule on the motions to remand. Also, shortly after the May 23, 2018 removal, the removing defendants filed motions with the United States Judicial Panel on Multidistrict Litigation (the “MDL Panel”) requesting that the Cameron Parish and Vermilion Parish lawsuits be consolidated with 40 similar lawsuits so that pre-trial proceedings in the cases could be coordinated. The MDL Panel denied the motion to consolidate the lawsuits. Due to the procedural posture of lawsuits, the cases are still in their early stages and the parties have conducted very little discovery. As a result, the Company has not had the opportunity to evaluate the applicability of the allegations made in plaintiffs' complaints to the Company's operations and management cannot determine the amount of loss, if any, that may result. In addition, due to the nature of the Company’s business, it is, from time to time, involved in routine litigation or subject to disputes or claims related to its business activities, including workers’ compensation claims and employment related disputes. In the opinion of the Company’s management, none of the pending litigation, disputes or claims against the Company, if decided adversely, will have a material adverse effect on its financial condition, cash flows or results of operations.

DERIVATIVE INSTRUMENTS

DERIVATIVE INSTRUMENTS	9 Months Ended
	Sep. 30, 2018
General Discussion of Derivative Instruments and Hedging Activities [Abstract]
DERIVATIVE INSTRUMENTS	DERIVATIVE INSTRUMENTS Natural Gas, Oil and Natural Gas Liquids Derivative Instruments The Company seeks to reduce its exposure to unfavorable changes in natural gas, oil and natural gas liquids ("NGLs") prices, which are subject to significant and often volatile fluctuation, by entering into over-the-counter fixed price swaps, basis swaps and various types of option contracts. These contracts allow the Company to predict with greater certainty the effective natural gas, oil and NGLs prices to be received for hedged production and benefit operating cash flows and earnings when market prices are less than the fixed prices provided in the contracts. However, the Company will not benefit from market prices that are higher than the fixed prices in the contracts for hedged production. Fixed price swaps are settled monthly based on differences between the fixed price specified in the contract and the referenced settlement price. When the referenced settlement price is less than the price specified in the contract, the Company receives an amount from the counterparty based on the price difference multiplied by the volume. Similarly, when the referenced settlement price exceeds the price specified in the contract, the Company pays the counterparty an amount based on the price difference multiplied by the volume. The prices contained in these fixed price swaps are based on the NYMEX Henry Hub for natural gas, Argus Louisiana Light Sweet Crude for oil, the NYMEX West Texas Intermediate for oil, and Mont Belvieu for propane, pentane and ethane. Below is a summary of the Company’s open fixed price swap positions as of September 30, 2018 . Location Daily Volume (MMBtu/day) Weighted Remaining 2018 NYMEX Henry Hub 1,010,000 $ 3.01 2019 NYMEX Henry Hub 1,154,000 $ 2.81 2020 NYMEX Henry Hub 204,000 $ 2.77 Location Daily Volume Weighted Remaining 2018 ARGUS LLS 2,000 $ 56.22 2019 ARGUS LLS 1,000 $ 59.55 Remaining 2018 NYMEX WTI 4,500 $ 53.72 2019 NYMEX WTI 4,000 $ 58.28 Location Daily Volume Weighted 2019 Mont Belvieu C2 1,000 $ 18.48 Remaining 2018 Mont Belvieu C3 4,000 $ 29.34 2019 Mont Belvieu C3 4,000 $ 28.87 Remaining 2018 Mont Belvieu C5 500 $ 46.62 2019 Mont Belvieu C5 500 $ 54.08 The Company sold call options and used the associated premiums to enhance the fixed price for a portion of the fixed price natural gas swaps listed above. Each short call option has an established ceiling price. When the referenced settlement price is above the price ceiling established by these short call options, the Company pays its counterparty an amount equal to the difference between the referenced settlement price and the price ceiling multiplied by the hedged contract volumes. Location Daily Volume (MMBtu/day) Weighted Average Price October 2018 - March 2019 NYMEX Henry Hub 50,000 $ 3.13 April 2019 - December 2019 NYMEX Henry Hub 30,000 $ 3.10 For a portion of the natural gas fixed price swaps listed above, the counterparty has an option to extend the original terms an additional twelve months for the period January 2019 through December 2019. The option to extend the terms expires in December 2018. If executed, the Company would have additional fixed price swaps for 100,000 MMBtu per day at a weighted average price of $3.05 per MMBtu. In addition, the Company entered into natural gas basis swap positions, which settle on the pricing index to basis differential of Transco Zone 4 to NYMEX Henry Hub natural gas price. As of September 30, 2018 , the Company had the following natural gas basis swap positions for Transco Zone 4. Location Daily Volume (MMBtu/day) Weighted Average Price Remaining 2018 Transco Zone 4 40,000 $ (0.05 ) 2019 Transco Zone 4 60,000 $ (0.05 ) 2020 Transco Zone 4 60,000 $ (0.05 ) Balance Sheet Presentation The Company reports the fair value of derivative instruments on the consolidated balance sheets as derivative instruments under current assets, noncurrent assets, current liabilities and noncurrent liabilities on a gross basis. The Company determines the current and noncurrent classification based on the timing of expected future cash flows of individual trades. The following table presents the fair value of the Company’s derivative instruments on a gross basis at September 30, 2018 and December 31, 2017 : September 30, 2018 December 31, 2017 (In thousands) Short-term derivative instruments - asset $ 19,809 $ 78,847 Long-term derivative instruments - asset $ 3,530 $ 8,685 Short-term derivative instruments - liability $ 62,601 $ 32,534 Long-term derivative instruments - liability $ 15,101 $ 2,989 Gains and Losses The following table presents the gain and loss recognized in net (loss) gain on natural gas, oil and NGL derivatives in the accompanying consolidated statements of operations for the three and nine months ended September 30, 2018 and 2017 . Net (loss) gain on derivative instruments Three months ended September 30, Nine months ended September 30, 2018 2017 2018 2017 (In thousands) Natural gas derivatives $ 14,101 $ (7,077 ) $ (26,789 ) $ 135,868 Oil derivatives (11,610 ) (6,571 ) (45,176 ) 12,477 Natural gas liquids derivatives (12,154 ) (9,212 ) (24,772 ) (6,757 ) Total $ (9,663 ) $ (22,860 ) $ (96,737 ) $ 141,588 Offsetting of derivative assets and liabilities As noted above, the Company records the fair value of derivative instruments on a gross basis. The following table presents the gross amounts of recognized derivative assets and liabilities in the consolidated balance sheets and the amounts that are subject to offsetting under master netting arrangements with counterparties, all at fair value. As of September 30, 2018 Gross Assets (Liabilities) Gross Amounts Presented in the Subject to Master Net Consolidated Balance Sheets Netting Agreements Amount (In thousands) Derivative assets $ 23,339 $ (17,053 ) $ 6,286 Derivative liabilities $ (77,702 ) $ 17,053 $ (60,649 ) As of December 31, 2017 Gross Assets (Liabilities) Gross Amounts Presented in the Subject to Master Net Consolidated Balance Sheets Netting Agreements Amount (In thousands) Derivative assets $ 87,532 $ (22,199 ) $ 65,333 Derivative liabilities $ (35,523 ) $ 22,199 $ (13,324 ) Concentration of Credit Risk By using derivative instruments that are not traded on an exchange, the Company is exposed to the credit risk of its counterparties. Credit risk is the risk of loss from counterparties not performing under the terms of the derivative instrument. When the fair value of a derivative instrument is positive, the counterparty is expected to owe the Company, which creates credit risk. To minimize the credit risk in derivative instruments, it is the Company’s policy to enter into derivative contracts only with counterparties that are creditworthy financial institutions deemed by management as competent and competitive market makers. The Company’s derivative contracts are with multiple counterparties to lessen its exposure to any individual counterparty. Additionally, the Company uses master netting agreements to minimize credit risk exposure. The creditworthiness of the Company’s counterparties is subject to periodic review. None of the Company’s derivative instrument contracts contain credit-risk related contingent features. Other than as provided by the Company’s revolving credit facility, the Company is not required to provide credit support or collateral to any of its counterparties under its derivative instruments, nor are the counterparties required to provide credit support to the Company.

FAIR VALUE MEASUREMENTS

FAIR VALUE MEASUREMENTS	9 Months Ended
	Sep. 30, 2018
Fair Value Disclosures [Abstract]
FAIR VALUE MEASUREMENTS	FAIR VALUE MEASUREMENTS The Company records certain financial and non-financial assets and liabilities on the balance sheet at fair value in accordance with ASC 820, Fair Value Measurement and Disclosures (“ASC 820”). ASC 820 defines fair value as the price that would be received to sell an asset or paid to transfer a liability (exit price) in an orderly transaction between market participants at the measurement date. The statement establishes market or observable inputs as the preferred sources of values, followed by assumptions based on hypothetical transactions in the absence of market inputs. The statement requires fair value measurements be classified and disclosed in one of the following categories: Level 1 – Quoted prices in active markets for identical assets and liabilities. Level 2 – Quoted prices in active markets for similar assets and liabilities, quoted prices for identical or similar instruments in markets that are not active and model-derived valuations whose inputs are observable or whose significant value drivers are observable. Level 3 – Significant inputs to the valuation model are unobservable. Valuation techniques that maximize the use of observable inputs are favored. Financial assets and liabilities are classified in their entirety based on the lowest level of input that is significant to the fair value measurement. The assessment of the significance of a particular input to the fair value measurement requires judgment and may affect the placement of assets and liabilities within the levels of the fair value hierarchy. Reclassifications of fair value between Level 1, Level 2 and Level 3 of the fair value hierarchy, if applicable, are made at the end of each quarter. The following tables summarize the Company’s financial and non-financial assets and liabilities by ASC 820 valuation level as of September 30, 2018 and December 31, 2017 : September 30, 2018 Level 1 Level 2 Level 3 (In thousands) Assets: Derivative Instruments $ — $ 23,339 $ — Liabilities: Derivative Instruments $ — $ 77,702 $ — December 31, 2017 Level 1 Level 2 Level 3 (In thousands) Assets: Derivative Instruments $ — $ 87,532 $ — Liabilities: Derivative Instruments $ — $ 35,523 $ — The Company estimates the fair value of all derivative instruments using industry-standard models that consider various assumptions, including current market and contractual prices for the underlying instruments, implied volatility, time value, nonperformance risk, as well as other relevant economic measures. Substantially all of these inputs are observable in the marketplace throughout the full term of the instrument and can be supported by observable data. The estimated fair values of proved oil and natural gas properties assumed in business combinations are based on a discounted cash flow model and market assumptions as to future commodity prices, projections of estimated quantities of oil and natural gas reserves, expectations for timing and amount of future development and operating costs, projections of future rates of production, expected recovery rates and risk-adjusted discount rates. The estimated fair values of unevaluated oil and natural gas properties was based on geological studies, historical well performance, location and applicable mineral lease terms. Based on the unobservable nature of certain of the inputs, the estimated fair value of the oil and gas properties assumed is deemed to use Level 3 inputs. The asset retirement obligations assumed as part of the business combination were estimated using the same assumptions and methodology as described below. See Note 1 for further discussion of the Vitruvian Acquisition. The Company estimates asset retirement obligations pursuant to the provisions of ASC Topic 410, Asset Retirement and Environmental Obligations (“ASC 410”). The initial measurement of asset retirement obligations at fair value is calculated using discounted cash flow techniques and based on internal estimates of future retirement costs associated with oil and gas properties. Given the unobservable nature of the inputs, including plugging costs and reserve lives, the initial measurement of the asset retirement obligation liability is deemed to use Level 3 inputs. See Note 2 for further discussion of the Company’s asset retirement obligations. Asset retirement obligations incurred during the nine months ended September 30, 2018 were approximately $1.5 million . The fair value of the common stock received from Mammoth Energy in connection with the Company’s contribution of all of its membership interests in Sturgeon, Stingray Energy and Stingray Cementing was estimated using Level 1 inputs, as the price per share was a quoted price in an active market for identical Mammoth Energy common shares.

FAIR VALUE OF FINANCIAL INSTRUM

FAIR VALUE OF FINANCIAL INSTRUMENTS	9 Months Ended
	Sep. 30, 2018
Investments, All Other Investments [Abstract]
FAIR VALUE OF FINANCIAL INSTRUMENTS	FAIR VALUE OF FINANCIAL INSTRUMENTS The carrying amounts on the accompanying consolidated balance sheet for cash and cash equivalents, accounts receivable, accounts payable and accrued liabilities, and current debt are carried at cost, which approximates market value due to their short-term nature. Long-term debt related to the Construction Loan is carried at cost, which approximates market value based on the borrowing rates currently available to the Company with similar terms and maturities. At September 30, 2018 , the carrying value of the outstanding debt represented by the Notes was approximately $2.0 billion , including the unamortized debt issuance cost of approximately $4.6 million related to the 2023 Notes, approximately $9.0 million related to the 2024 Notes, approximately $12.9 million related to the 2025 Notes and approximately $5.2 million related to the 2026 Notes. Based on the quoted market price, the fair value of the Notes was determined to be approximately $2.0 billion at September 30, 2018 .

REVENUE FROM CONTRACTS WITH CUS

REVENUE FROM CONTRACTS WITH CUSTOMERS	9 Months Ended
	Sep. 30, 2018
Revenue from Contract with Customer [Abstract]
REVENUE FROM CONTRACTS WITH CUSTOMERS	REVENUE FROM CONTRACTS WITH CUSTOMERS Revenue Recognition On January 1, 2018, the Company adopted Accounting Standards Update ("ASU") No. 2014-09, Revenue from Contracts with Customers ("ASC 606") using the modified retrospective transition applied to contracts that were not completed as of that date. The adoption did not result in a material change in the Company’s accounting or have a material effect on the Company’s financial position, including measurement of revenue, the timing of revenue recognition and the recognition of contract assets, liabilities and related costs. For periods through December 31, 2017, the Company accounted for its revenue using ASC 605, Revenue Recognition . The Company’s revenues are primarily derived from the sale of natural gas, oil and condensate and NGLs. Sales of natural gas, oil and condensate and NGLs are recognized in the period that the performance obligations are satisfied. The Company generally considers the delivery of each unit (MMBtu or Bbl) to be separately identifiable and represents a distinct performance obligation that is satisfied at a point-in-time once control of the product has been transferred to the customer. The Company considers a variety of facts and circumstances in assessing the point of control transfer, including but not limited to (i) whether the purchaser can direct the use of the product, (ii) the transfer of significant risks, (iii) the Company’s right to payment and (iv) transfer of legal title. Revenue is measured based on consideration specified in the contract with the customer, and excludes any amounts collected on behalf of third parties. These contracts typically include variable consideration that is based on pricing tied to market indices and volumes delivered in the current month. As such, this market pricing may be constrained (i.e., not estimable) at the inception of the contract but will be recognized based on the applicable market pricing, which will be known upon transfer of the goods to the customer. The payment date is usually within 30 days of the end of the calendar month in which the commodity is delivered. The recognition of gains or losses on derivative instruments is outside the scope of ASC 606 and is not considered revenue from contracts with customers subject to ASC 606. The Company may use financial or physical contracts accounted for as derivatives as economic hedges to manage price risk associated with normal sales, or in limited cases may use them for contracts the Company intends to physically settle but do not meet all of the criteria to be treated as normal sales. The Company has elected to exclude from the measurement of the transaction price all taxes assessed by governmental authorities that are both imposed on and concurrent with a specific revenue-producing transaction and collected by the Company from a customer, such as sales tax, use tax, value-added tax and similar taxes. Transaction Price Allocated to Remaining Performance Obligations A significant number of the Company's product sales are short-term in nature generally through evergreen contracts with contract terms of one year or less. These contracts typically automatically renew under the same provisions. For those contracts, the Company has utilized the practical expedient allowed in the new revenue accounting standard that exempts the Company from disclosure of the transaction price allocated to remaining performance obligations if the performance obligation is part of a contract that has an original expected duration of one year or less. For product sales that have a contract term greater than one year, the Company has utilized the practical expedient that exempts the Company from disclosure of the transaction price allocated to remaining performance obligations if the variable consideration is allocated entirely to a wholly unsatisfied performance obligation. Under these sales contracts, each unit of product generally represents a separate performance obligation; therefore, future volumes are wholly unsatisfied and disclosure of the transaction price allocated to remaining performance obligations is not required. Currently, the Company's product sales that have a contractual term greater than one year have no long-term fixed consideration. Contract Balances Receivables from contracts with customers are recorded when the right to consideration becomes unconditional, generally when control of the product has been transferred to the customer. Receivables from contracts with customers were $157.4 million and $146.8 million as of September 30, 2018 and December 31, 2017 , respectively, and are reported in accounts receivable - oil and natural gas sales on the consolidated balance sheet. The Company currently has no assets or liabilities related to its revenue contracts, including no upfront or rights to deficiency payments. Contract Modifications For contracts modified prior to the beginning of the earliest reporting period presented under ASC 606, the Company has elected to reflect the aggregate of the effect of all modifications that occurred before the beginning of the earliest period presented under the new standard when identifying the satisfied and unsatisfied performance obligations, determining the transaction price and allocating the transaction price to the satisfied and unsatisfied performance obligations for the modified contracts at transition. Prior-Period Performance Obligations The Company records revenue in the month production is delivered to the purchaser. However, settlement statements for certain gas and NGLs sales may be received for 30 to 90 days after the date production is delivered, and as a result, the Company is required to estimate the amount of production that was delivered to the purchaser and the price that will be received for the sale of the product. The differences between the estimates and the actual amounts for product sales is recorded in the month that payment is received from the purchaser. The Company has internal controls in place for the estimation process and any identified differences between revenue estimates and actual revenue received historically have not been significant. For the nine months ended September 30, 2018 , revenue recognized in the reporting period related to performance obligations satisfied in prior reporting periods was not material.

INCOME TAXES

INCOME TAXES	9 Months Ended
	Sep. 30, 2018
Income Tax Disclosure [Abstract]
INCOME TAXES	INCOME TAXES The Company records its quarterly tax provision based on an estimate of the annual effective tax rate expected to apply to continuing operations for the various jurisdictions in which it operates. The tax effects of certain items, such as tax rate changes, significant unusual or infrequent items, and certain changes in the assessment of the realizability of deferred taxes, are recognized as discrete items in the period in which they occur and are excluded from the estimated annual effective tax rate. For the three and nine months ended September 30, 2018 , the Company's estimated annual effective tax rate remained nominal as a result of the full valuation allowance on deferred tax assets. Based on the Company's estimated results for the year ending December 31, 2018, the Company anticipates remaining in a net deferred tax asset position. Based on the available positive and negative evidence, the Company expects to maintain a full valuation allowance as it cannot objectively assert that the deferred tax assets are more likely than not to be realized. A significant piece of negative evidence is the cumulative loss incurred over the three year period ending September 30, 2018 . However, given the Company's current earnings and anticipated future earnings, it believes that there is a reasonable possibility that within the next 12 months sufficient positive evidence regarding recent cumulative income may become available, which may allow it to reach a conclusion that a significant portion of the valuation allowance will no longer be needed. Release of the valuation allowance would result in the recognition of certain net deferred tax assets and a decrease to income tax expense for the period the release is recorded. However, the exact timing and amount of any potential valuation allowance release is subject to change based on the levels of profitability that the Company is able to actually achieve. On December 22, 2017, the President of the United States signed into law Public Law No. 115-97, a comprehensive tax reform bill commonly referred to as the Tax Cuts and Jobs Act ("Tax Act") that significantly reformed the Internal Revenue Code of 1986, as amended. The Tax Act substantially revised numerous areas of U.S. federal income tax law, including reducing the maximum corporate income tax rate from 35% to 21%, allowing for full expensing of certain capital expenditures, modifying the limitations on the utilization of net operating losses, and repealing the corporate alternative minimum tax. The various estimates included in determining the Company's tax provision as of December 31, 2017 remain provisional through the nine months ended September 30, 2018 and may be adjusted through subsequent events such as the filing of its 2017 consolidated federal income tax return and the issuance of additional guidance from the Internal Revenue Service or from state tax authorities. There were no material changes to the provisional estimates during the quarter ended September 30, 2018 .

CONDENSED CONSOLIDATING FINANCI

CONDENSED CONSOLIDATING FINANCIAL INFORMATION	9 Months Ended
	Sep. 30, 2018
Condensed Financial Information Disclosure [Abstract]
CONDENSED CONSOLIDATING FINANCIAL INFORMATION	CONDENSED CONSOLIDATING FINANCIAL INFORMATION On April 21, 2015, the Company issued $350.0 million in aggregate principal amount of the 2023 Notes to qualified institutional buyers pursuant to Rule 144A under the Securities Act and to certain non-U.S. persons in accordance with Regulation S under the Securities Act. In connection with the 2023 Notes Offering, the Company and its subsidiary guarantors entered into a registration rights agreement, dated as of April 21, 2015, pursuant to which the Company agreed to file a registration statement with respect to an offer to exchange the 2023 Notes for a new issue of substantially identical debt securities registered under the Securities Act. The exchange offer for the 2023 Notes was completed on October 13, 2015. On October 14, 2016, the Company issued $650.0 million in aggregate principal amount of the 2024 Notes to qualified institutional buyers pursuant to Rule 144A under the Securities Act and to certain non-U.S. persons in accordance with Regulation S under the Securities Act. The net proceeds from the issuance of the 2024 Notes, together with cash on hand, were used to repurchase or redeem all of the then-outstanding 2020 Notes in October 2016. On December 21, 2016, the Company issued $600.0 million in aggregate principal amount of the 2025 Notes to qualified institutional buyers pursuant to Rule 144A under the Securities Act and to certain non-U.S. persons in accordance with Regulation S under the Securities Act. The Company used the net proceeds from the issuance of the 2025 Notes, together with the net proceeds from the December 2016 underwritten offering of the Company’s common stock and cash on hand, to fund the cash portion of the purchase price for the Vitruvian Acquisition. In connection with the 2024 Notes and the 2025 Notes Offerings, the Company and its subsidiary guarantors entered into two registration rights agreements, pursuant to which the Company agreed to file a registration statement with respect to offers to exchange the 2024 Notes and the 2025 Notes for new issues of substantially identical debt securities registered under the Securities Act. The exchange offers for the 2024 Notes and the 2025 Notes were completed on September 13, 2017. On October 11, 2017, the Company issued $450.0 million in aggregate principal amount of the 2026 Notes to qualified institutional buyers pursuant to Rule 144A under the Securities Act and to certain non-U.S. persons in accordance with Regulation S under the Securities Act. A portion of the net proceeds from the issuance of the 2026 Notes was used to repay all of the Company's outstanding borrowings under its secured revolving credit facility on October 11, 2017 and the balance was used to fund the remaining outspend related to the Company's 2017 capital development plans. In connection with the 2026 Notes offering, the Company and its subsidiary guarantors entered into a registration rights agreement pursuant to which the Company agreed to file a registration statement with respect to an offer to exchange the 2026 Notes for a new issue of substantially identical debt securities registered under the Securities Act. On January 18, 2018, the Company filed a registration statement on Form S-4 with respect to an offer to exchange the 2026 Notes for substantially identical debt securities registered under the Securities Act, which registration statement was declared effective by the SEC on February 12, 2018. The exchange offer relating to the 2026 notes closed on March 22, 2018. The 2023 Notes, the 2024 Notes, the 2025 Notes and the 2026 Notes are guaranteed on a senior unsecured basis by all existing consolidated subsidiaries that guarantee the Company’s secured revolving credit facility or certain other debt (the “Guarantors”). The 2023 Notes, the 2024 Notes, the 2025 Notes and the 2026 Notes are not guaranteed by Grizzly Holdings, Inc. (the “Non-Guarantor”). The Guarantors are 100% owned by Gulfport (the “Parent”), and the guarantees are full, unconditional, joint and several. There are no significant restrictions on the ability of the Parent or the Guarantors to obtain funds from each other in the form of a dividend or loan. The following condensed consolidating balance sheets, statements of operations, statements of comprehensive income and statements of cash flows are provided for the Parent, the Guarantors and the Non-Guarantor and include the consolidating adjustments and eliminations necessary to arrive at the information for the Company on a condensed consolidated basis. The information has been presented using the equity method of accounting for the Parent’s ownership of the Guarantors and the Non-Guarantor. CONDENSED CONSOLIDATING BALANCE SHEETS (Amounts in thousands) September 30, 2018 Parent Guarantors Non-Guarantor Eliminations Consolidated Assets Current assets: Cash and cash equivalents $ 89,214 $ 35,357 $ — $ — $ 124,571 Accounts receivable - oil and natural gas sales 111,463 45,928 — — 157,391 Accounts receivable - joint interest and other 19,066 20,445 — — 39,511 Accounts receivable - related parties 79 — — — 79 Accounts receivable - intercompany 662,319 240,373 — (902,692 ) — Prepaid expenses and other current assets 7,521 2,221 — — 9,742 Short-term derivative instruments 19,809 — — — 19,809 Total current assets 909,471 344,324 — (902,692 ) 351,103 Property and equipment: Oil and natural gas properties, full-cost accounting 7,003,396 2,934,047 — (729 ) 9,936,714 Other property and equipment 91,637 751 — — 92,388 Accumulated depletion, depreciation, amortization and impairment (4,506,267 ) (39 ) — — (4,506,306 ) Property and equipment, net 2,588,766 2,934,759 — (729 ) 5,522,796 Other assets: Equity investments and investments in subsidiaries 2,723,140 — 53,380 (2,543,991 ) 232,529 Long-term derivative instruments 3,530 — — — 3,530 Inventories 6,800 1,434 — — 8,234 Other assets 13,018 4,020 — — 17,038 Total other assets 2,746,488 5,454 53,380 (2,543,991 ) 261,331 Total assets $ 6,244,725 $ 3,284,537 $ 53,380 $ (3,447,412 ) $ 6,135,230 Liabilities and Stockholders ’ Equity Current liabilities: Accounts payable and accrued liabilities $ 464,426 $ 118,038 $ — $ — $ 582,464 Accounts payable - intercompany 240,310 662,254 128 (902,692 ) — Asset retirement obligation - current 120 — — — 120 Short-term derivative instruments 62,601 — — — 62,601 Current maturities of long-term debt 647 — — — 647 Total current liabilities 768,104 780,292 128 (902,692 ) 645,832 Long-term derivative instruments 15,101 — — — 15,101 Asset retirement obligation - long-term 65,634 12,777 — — 78,411 Deferred tax liability 3,046 — — — 3,046 Long-term debt, net of current maturities 2,100,825 — — — 2,100,825 Total liabilities 2,952,710 793,069 128 (902,692 ) 2,843,215 Stockholders’ equity: Common stock 1,732 — — — 1,732 Paid-in capital 4,316,006 1,915,598 261,626 (2,177,224 ) 4,316,006 Accumulated other comprehensive (loss) income (46,354 ) — (44,338 ) 44,338 (46,354 ) Retained (deficit) earnings (979,369 ) 575,870 (164,036 ) (411,834 ) (979,369 ) Total stockholders’ equity 3,292,015 2,491,468 53,252 (2,544,720 ) 3,292,015 Total liabilities and stockholders ’ equity $ 6,244,725 $ 3,284,537 $ 53,380 $ (3,447,412 ) $ 6,135,230 CONDENSED CONSOLIDATING BALANCE SHEETS (Amounts in thousands) December 31, 2017 Parent Guarantors Non-Guarantor Eliminations Consolidated Assets Current assets: Cash and cash equivalents $ 67,908 $ 31,649 $ — $ — $ 99,557 Accounts receivable - oil and natural gas sales 112,686 34,087 — — 146,773 Accounts receivable - joint interest and other 15,435 20,005 — — 35,440 Accounts receivable - intercompany 554,439 63,374 — (617,813 ) — Prepaid expenses and other current assets 4,719 193 — — 4,912 Short-term derivative instruments 78,847 — — — 78,847 Total current assets 834,034 149,308 — (617,813 ) 365,529 Property and equipment: Oil and natural gas properties, full-cost accounting, 6,562,147 2,607,738 — (729 ) 9,169,156 Other property and equipment 86,711 43 — — 86,754 Accumulated depletion, depreciation, amortization and impairment (4,153,696 ) (37 ) — — (4,153,733 ) Property and equipment, net 2,495,162 2,607,744 — (729 ) 5,102,177 Other assets: Equity investments and investments in subsidiaries 2,361,575 77,744 57,641 (2,194,848 ) 302,112 Long-term derivative instruments 8,685 — — — 8,685 Deferred tax asset 1,208 — — — 1,208 Inventories 5,816 2,411 — — 8,227 Other assets 12,483 7,331 — — 19,814 Total other assets 2,389,767 87,486 57,641 (2,194,848 ) 340,046 Total assets $ 5,718,963 $ 2,844,538 $ 57,641 $ (2,813,390 ) $ 5,807,752 Liabilities and Stockholders ’ Equity Current liabilities: Accounts payable and accrued liabilities $ 416,249 $ 137,361 $ — $ (1 ) $ 553,609 Accounts payable - intercompany 63,373 554,313 127 (617,813 ) — Asset retirement obligation - current 120 — — — 120 Short-term derivative instruments 32,534 — — — 32,534 Current maturities of long-term debt 622 — — — 622 Total current liabilities 512,898 691,674 127 (617,814 ) 586,885 Long-term derivative instruments 2,989 — — — 2,989 Asset retirement obligation - long-term 63,141 11,839 — — 74,980 Other non-current liabilities — 2,963 — — 2,963 Long-term debt, net of current maturities 2,038,321 — — — 2,038,321 Total liabilities 2,617,349 706,476 127 (617,814 ) 2,706,138 Stockholders’ equity: Common stock 1,831 — — — 1,831 Paid-in capital 4,416,250 1,915,598 259,307 (2,174,905 ) 4,416,250 Accumulated other comprehensive (loss) income (40,539 ) — (38,593 ) 38,593 (40,539 ) Retained (deficit) earnings (1,275,928 ) 222,464 (163,200 ) (59,264 ) (1,275,928 ) Total stockholders’ equity 3,101,614 2,138,062 57,514 (2,195,576 ) 3,101,614 Total liabilities and stockholders ’ equity $ 5,718,963 $ 2,844,538 $ 57,641 $ (2,813,390 ) $ 5,807,752 CONDENSED CONSOLIDATING STATEMENTS OF OPERATIONS (Amounts in thousands) Three months ended September 30, 2018 Parent Guarantors Non-Guarantor Eliminations Consolidated Total revenues $ 235,683 $ 125,279 $ — $ — $ 360,962 Costs and expenses: Lease operating expenses 16,502 5,823 — — 22,325 Production taxes 4,505 4,843 — — 9,348 Midstream gathering and processing 54,397 24,516 — — 78,913 Depreciation, depletion and amortization 119,914 1 — — 119,915 General and administrative 16,314 (467 ) 1 — 15,848 Accretion expense 812 225 — — 1,037 212,444 34,941 1 — 247,386 INCOME (LOSS) FROM OPERATIONS 23,239 90,338 (1 ) — 113,576 OTHER (INCOME) EXPENSE: Interest expense 34,254 (1,001 ) — — 33,253 Interest income (86 ) (6 ) — — (92 ) Litigation settlement 917 — — — 917 Gain on sale of equity method investments (2,733 ) — — — (2,733 ) (Income) loss from equity method investments and investments in subsidiaries (104,226 ) (1 ) 275 91,094 (12,858 ) Other income (37 ) (24 ) — — (61 ) (71,911 ) (1,032 ) 275 91,094 18,426 INCOME (LOSS) BEFORE INCOME TAXES 95,150 91,370 (276 ) (91,094 ) 95,150 INCOME TAX BENEFIT — — — — — NET INCOME (LOSS) $ 95,150 $ 91,370 $ (276 ) $ (91,094 ) $ 95,150 CONDENSED CONSOLIDATING STATEMENTS OF OPERATIONS (Amounts in thousands) Three months ended September 30, 2017 Parent Guarantors Non-Guarantor Eliminations Consolidated Total revenues $ 188,390 $ 77,108 $ — $ — $ 265,498 Costs and expenses: Lease operating expenses 16,019 4,001 — — 20,020 Production taxes 4,052 1,367 — — 5,419 Midstream gathering and processing 52,725 16,647 — — 69,372 Depreciation, depletion and amortization 106,649 1 — — 106,650 General and administrative 13,956 (892 ) 1 — 13,065 Accretion expense 335 121 — — 456 Acquisition expense (5 ) 38 — — 33 193,731 21,283 1 — 215,015 (LOSS) INCOME FROM OPERATIONS (5,341 ) 55,825 (1 ) — 50,483 OTHER (INCOME) EXPENSE: Interest expense 27,914 (784 ) — — 27,130 Interest income (29 ) (8 ) — — (37 ) (Income) loss from equity method investments and investments in subsidiaries (53,880 ) 128 296 56,193 2,737 Other income (344 ) (1 ) — — (345 ) (26,339 ) (665 ) 296 56,193 29,485 INCOME (LOSS) BEFORE INCOME TAXES 20,998 56,490 (297 ) (56,193 ) 20,998 INCOME TAX EXPENSE 2,763 — — — 2,763 NET INCOME (LOSS) $ 18,235 $ 56,490 $ (297 ) $ (56,193 ) $ 18,235 CONDENSED CONSOLIDATING STATEMENTS OF OPERATIONS (Amounts in thousands) Nine months ended September 30, 2018 Parent Guarantors Non-Guarantor Eliminations Consolidated Total revenues $ 596,018 $ 343,076 $ — $ — $ 939,094 Costs and expenses: Lease operating expenses 46,926 17,217 — — 64,143 Production taxes 13,309 10,552 — — 23,861 Midstream gathering and processing 152,605 61,941 — — 214,546 Depreciation, depletion, and amortization 352,846 2 — — 352,848 General and administrative 45,100 (2,148 ) 3 — 42,955 Accretion expense 2,397 659 — — 3,056 613,183 88,223 3 — 701,409 (LOSS) INCOME FROM OPERATIONS (17,165 ) 254,853 (3 ) — 237,685 OTHER (INCOME) EXPENSE: Interest expense 103,310 (2,388 ) — — 100,922 Interest income (144 ) (18 ) — — (162 ) Litigation settlement 917 — — — 917 Insurance proceeds (231 ) — — — (231 ) Gain on sale of equity method investments (28,349 ) (96,419 ) — — (124,768 ) (Income) loss from equity method investments and investments in subsidiaries (387,991 ) (694 ) 833 352,570 (35,282 ) Other (income) expense (1,167 ) (34 ) — 1,000 (201 ) (313,655 ) (99,553 ) 833 353,570 (58,805 ) INCOME (LOSS) BEFORE INCOME TAXES 296,490 354,406 (836 ) (353,570 ) 296,490 INCOME TAX BENEFIT (69 ) — — — (69 ) NET INCOME (LOSS) $ 296,559 $ 354,406 $ (836 ) $ (353,570 ) $ 296,559 CONDENSED CONSOLIDATING STATEMENTS OF OPERATIONS (Amounts in thousands) Nine months ended September 30, 2017 Parent Guarantors Non-Guarantor Eliminations Consolidated Total revenues $ 710,184 $ 212,271 $ — $ — $ 922,455 Costs and expenses: Lease operating expenses 49,891 10,153 — — 60,044 Production taxes 10,799 3,665 — — 14,464 Midstream gathering and processing 132,740 43,518 — — 176,258 Depreciation, depletion, and amortization 254,884 3 — — 254,887 General and administrative 39,882 (1,963 ) 3 — 37,922 Accretion expense 908 240 — — 1,148 Acquisition expense — 2,391 — — 2,391 489,104 58,007 3 — 547,114 INCOME (LOSS) FROM OPERATIONS 221,080 154,264 (3 ) — 375,341 OTHER (INCOME) EXPENSE: Interest expense 79,095 (4,298 ) — — 74,797 Interest income (913 ) (14 ) — — (927 ) Gain on sale of equity method investments (12,523 ) — — — (12,523 ) (Income) loss from equity method investments and investments in subsidiaries (124,446 ) 2,586 869 154,459 33,468 Other (income) expense (1,522 ) (241 ) — 900 (863 ) (60,309 ) (1,967 ) 869 155,359 93,952 INCOME (LOSS) BEFORE INCOME TAXES 281,389 156,231 (872 ) (155,359 ) 281,389 INCOME TAX EXPENSE 2,763 — — — 2,763 NET INCOME (LOSS) $ 278,626 $ 156,231 $ (872 ) $ (155,359 ) $ 278,626 CONDENSED CONSOLIDATING STATEMENTS OF COMPREHENSIVE INCOME (LOSS) (Amounts in thousands) Three months ended September 30, 2018 Parent Guarantors Non-Guarantor Eliminations Consolidated Net income (loss) $ 95,150 $ 91,370 $ (276 ) $ (91,094 ) $ 95,150 Foreign currency translation adjustment 3,052 103 2,949 (3,052 ) 3,052 Other comprehensive income (loss) 3,052 103 2,949 (3,052 ) 3,052 Comprehensive income (loss) $ 98,202 $ 91,473 $ 2,673 $ (94,146 ) $ 98,202 Three months ended September 30, 2017 Parent Guarantors Non-Guarantor Eliminations Consolidated Net income (loss) $ 18,235 $ 56,490 $ (297 ) $ (56,193 ) $ 18,235 Foreign currency translation adjustment 6,832 158 6,674 (6,832 ) 6,832 Other comprehensive income (loss) 6,832 158 6,674 (6,832 ) 6,832 Comprehensive income (loss) $ 25,067 $ 56,648 $ 6,377 $ (63,025 ) $ 25,067 Nine months ended September 30, 2018 Parent Guarantors Non-Guarantor Eliminations Consolidated Net income (loss) $ 296,559 $ 354,406 $ (836 ) $ (353,570 ) $ 296,559 Foreign currency translation adjustment (5,815 ) (70 ) (5,745 ) 5,815 (5,815 ) Other comprehensive (loss) income (5,815 ) (70 ) (5,745 ) 5,815 (5,815 ) Comprehensive income (loss) $ 290,744 $ 354,336 $ (6,581 ) $ (347,755 ) $ 290,744 Nine months ended September 30, 2017 Parent Guarantors Non-Guarantor Eliminations Consolidated Net income (loss) $ 278,626 $ 156,231 $ (872 ) $ (155,359 ) $ 278,626 Foreign currency translation adjustment 12,719 232 12,487 (12,719 ) 12,719 Other comprehensive income (loss) 12,719 232 12,487 (12,719 ) 12,719 Comprehensive income (loss) $ 291,345 $ 156,463 $ 11,615 $ (168,078 ) $ 291,345 CONDENSED CONSOLIDATING STATEMENTS OF CASH FLOWS (Amounts in thousands) Nine months ended September 30, 2018 Parent Guarantors Non-Guarantor Eliminations Consolidated Net cash provided by (used in) operating activities $ 416,833 $ 192,123 $ (1 ) $ 1 $ 608,956 Net cash (used in) provided by investing activities (344,330 ) (188,415 ) (2,318 ) 2,318 (532,745 ) Net cash (used in) provided by financing activities (51,197 ) — 2,319 (2,319 ) (51,197 ) Net increase in cash, cash equivalents and restricted cash 21,306 3,708 — — 25,014 Cash, cash equivalents and restricted cash at beginning of period 67,908 31,649 — — 99,557 Cash, cash equivalents and restricted cash at end of period $ 89,214 $ 35,357 $ — $ — $ 124,571 Nine months ended September 30, 2017 Parent Guarantors Non-Guarantor Eliminations Consolidated Net cash provided by (used in) operating activities $ 310,624 $ 181,108 $ (1 ) $ 2 $ 491,733 Net cash (used in) provided by investing activities (2,034,554 ) (1,554,063 ) (1,843 ) 1,408,980 (2,181,480 ) Net cash provided by (used in) financing activities 354,143 1,407,137 1,845 (1,408,982 ) 354,143 Net (decrease) increase in cash, cash equivalents and restricted cash (1,369,787 ) 34,182 1 — (1,335,604 ) Cash, cash equivalents and restricted cash at beginning of period 1,458,882 1,993 — — 1,460,875 Cash, cash equivalents and restricted cash at end of period $ 89,095 $ 36,175 $ 1 $ — $ 125,271

RECENT ACCOUNTING PRONOUNCEMENT

RECENT ACCOUNTING PRONOUNCEMENTS	9 Months Ended
	Sep. 30, 2018
Accounting Changes and Error Corrections [Abstract]
RECENT ACCOUNTING PRONOUNCEMENTS	RECENT ACCOUNTING PRONOUNCEMENTS In May 2014 , the Financial Accounting Standards Board (“FASB”) issued ASC 606 . ASC 606 supersedes existing industry specific revenue recognition guidance and increases disclosure requirements. The core principle of the new standard is for the recognition of revenue to depict the transfer of goods or services to customers in amounts that reflect the payment to which the company expects to be entitled in exchange for those goods or services. The Company adopted ASC 606 as of January 1, 2018 using the modified retrospective transition method applied to contracts that were not completed as of that date. Results for reporting periods beginning after January 1, 2018 are presented under the new revenue standard. Under the modified retrospective method, the Company recognizes the cumulative effect of initially applying the new revenue standard as an adjustment to the opening balance of retained earnings; however, no adjustment was required as a result of adopting the new revenue standard. The comparative information has not been restated and continues to be reported under the historic accounting standards in effect for those periods. The impact of the adoption of the new revenue standard is not expected to be material to the Company’s net income on an ongoing basis. In February 2016, the FASB issued ASU No. 2016-02 , Leases (Topic 842) . The standard supersedes the previous lease guidance by requiring lessees to recognize a right-to-use asset and lease liability on the balance sheet for all leases with lease terms of greater than one year while maintaining substantially similar classifications for financing and operating leases. The guidance is effective for periods after December 15, 2018 , and the Company will not early adopt. The Company expects to apply the transition method permitted by ASU No. 2018-11 , Leases (Topic 842): Targeted Improvements , issued in August 2018, which permits an entity to recognize a cumulative-effect adjustment to the opening balance of retained earnings in the period of adoption with no adjustment made to the comparative periods presented in the consolidated financial statements. The Company also expects to utilize the practical expedient provided by ASU 2018-11 to not separate non-lease components from the associated lease component and, instead, to account for those components as a single component if the non-lease components would be accounted for under ASC 606 and other conditions are met. The Company has identified its portfolio of leased assets under the new standard and is in the process of evaluating the impact of this guidance on its consolidated financial statements and related disclosures. The adoption will increase asset and liability balances on the consolidated balance sheets due to the required recognition of right-of-use assets and corresponding lease liabilities; however, that impact is currently not known. The Company is in the process of designing processes and controls needed to comply with the requirements of the new standard, which includes the implementation of a lease accounting software solution to support lease portfolio management and accounting and disclosures. Additionally, in January 2018 , the FASB issued ASU No. 2018-01 , Leases (Topic 842): Land Easement Practical Expedient for Transition to Topic 842 . The amendments in this update provide an optional expedient to not evaluate existing or expired land easements that were not previously accounted for under current leases guidance in Topic 840. An entity that elects this practical expedient should evaluate new or modified land easements beginning at the date of adoption. The Company does not currently account for any land easements under Topic 840 and plans to utilize this practical expedient in conjunction with the adoption of ASU 2016-02. In June 2016 , the FASB issued ASU No. 2016-13 , Financial Instruments-Credit Losses: Measurement of Credit Losses on Financial Instruments . This ASU amends guidance on reporting credit losses for assets held at amortized cost basis and available for sale debt securities. For assets held at amortized cost basis, this ASU eliminates the probable initial recognition threshold in current GAAP and instead, requires an entity to reflect its current estimate of all expected credit losses. The amendments affect loans, debt securities, trade receivables, net investments in leases, off balance sheet credit exposure, reinsurance receivables and any other financial assets not excluded from the scope that have the contractual right to receive cash. The guidance is effective for periods after December 15, 2019, with early adoption permitted. The Company is currently evaluating the impact this standard will have on its financial statements and related disclosures and does not anticipate it to have a material effect. In August 2016 , the FASB issued ASU No. 2016-15 , Statement of Cash Flows: Classification of Certain Cash Receipts and Cash Payments . This ASU clarifies how certain cash receipts and cash payments should be classified and presented in the statement of cash flows. The Company adopted this standard in the first quarter of 2018 and has made an accounting policy election to classify distributions received from equity method investees using the nature of the distribution approach, which classifies distributions received from investees as either cash inflows from operating activities or cash inflows from investing activities in the statement of cash flows based on the nature of the activities of the investee that generated the distribution. The impact of adopting this ASU was not material to prior periods presented. In November 2016 , the FASB issued ASU No. 2016-18, Statement of Cash Flows (Topic 230): Restricted Cash . This ASU requires that amounts generally described as restricted cash and restricted cash equivalents be included with cash and cash equivalents when reconciling the beginning-of-period and end-of-period amounts shown on the statement of cash flows and to provide a reconciliation of the totals in the statement of cash flows to the related captions in the balance sheet when the cash, cash equivalents, restricted cash, and restricted cash equivalents are presented in more than one line item on the balance sheet. The Company adopted this standard in the first quarter of 2018 using the retrospective transition method. The adoption of this standard had no impact on the statement of cash flows for the nine months ended September 30, 2018 and resulted in the addition of $185.0 million of restricted cash to the beginning cash balance and an increase to net cash used in investing activities by the same amount on the statement of cash flows for the nine months ended September 30, 2017 . In January 2017 , the FASB issued ASU No. 2017-01 , Clarifying the Definition of a Business . Under the current business combination guidance, there are three elements of a business: inputs, processes and outputs. The revised guidance adds an initial screen test to determine if substantially all of the fair value of the gross assets acquired is concentrated in a single asset or group of similar assets. If that screen is met, the set of assets is not a business. The new framework also specifies the minimum required inputs and processes necessary to be a business. The Company adopted this standard in the first quarter of 2018 with no significant effect on its financial statements or related disclosures. In February 2018 , the FASB issued ASU No. 2018-02 , Income statement - Reporting Comprehensive Income (Topic 220) - Reclassification of Certain Tax Effects from Accumulated Other Comprehensive Income , which allows a reclassification from accumulated other comprehensive income to retained earnings for standard tax effects resulting from the Tax Cuts and Jobs Act of 2017. The amendment will be effective for reporting periods beginning after December 15, 2018 , and early adoption is permitted. The Company is currently assessing the impact of the ASU on its consolidated financial statements and related disclosures. In August 2018 , the FASB issued ASU No. 2018-13 , Fair Value Measurement (Topic 820): Disclosure Framework—Changes to the Disclosure Requirements for Fair Value Measurement which removes, modifies, and adds certain disclosure requirements on fair value measurements. The amendment will be effective for reporting periods beginning after December 15, 2019 , and early adoption is permitted. The Company is currently assessing the impact of the ASU on its consolidated financial statements and related disclosures. In August 2018 , the FASB also issued ASU No. 2018-15 , Intangibles—Goodwill and Other—Internal-Use Software (Subtopic 350-40): Customer’s Accounting for Implementation Costs Incurred in a Cloud Computing Arrangement That Is a Service Contract , which aligns the accounting for costs associated with implementing a cloud computing arrangement in a hosting arrangement that is a service contract with the accounting for implementation costs incurred to develop or obtain internal-use software. The amendment will be effective for reporting periods beginning after December 15, 2019 , and early adoption is permitted. The Company is currently assessing the impact of the ASU on its consolidated financial statements and related disclosures.

SUBSEQUENT EVENTS

SUBSEQUENT EVENTS	9 Months Ended
	Sep. 30, 2018
Subsequent Events [Abstract]
SUBSEQUENT EVENTS	SUBSEQUENT EVENTS At September 30, 2018, accounts receivable-related parties totaled $79,000 and represented personal charges made by the former chief executive officer of the Company on his Company credit card. These charges were paid in full in October 2018 and no personal charges are currently outstanding.

RECENT ACCOUNTING PRONOUNCEME_2

RECENT ACCOUNTING PRONOUNCEMENTS (Policies)	9 Months Ended
	Sep. 30, 2018
Accounting Changes and Error Corrections [Abstract]
Consolidation, variable interest entity, policy	The Company accounts for its investment in these VIEs following the equity method of accounting. The carrying amounts of the Company’s equity investments are classified as other non-current assets on the accompanying consolidated balance sheets. The Company’s maximum exposure to loss as a result of its involvement with these VIEs is based on the Company’s capital contributions and the economic performance of the VIEs, and is equal to the carrying value of the Company’s investments which is the maximum loss the Company could be required to record in the consolidated statements of operations. See Note 3 for further discussion of these entities, including the carrying amounts of each investment.
Recent accounting pronouncements	In May 2014 , the Financial Accounting Standards Board (“FASB”) issued ASC 606 . ASC 606 supersedes existing industry specific revenue recognition guidance and increases disclosure requirements. The core principle of the new standard is for the recognition of revenue to depict the transfer of goods or services to customers in amounts that reflect the payment to which the company expects to be entitled in exchange for those goods or services. The Company adopted ASC 606 as of January 1, 2018 using the modified retrospective transition method applied to contracts that were not completed as of that date. Results for reporting periods beginning after January 1, 2018 are presented under the new revenue standard. Under the modified retrospective method, the Company recognizes the cumulative effect of initially applying the new revenue standard as an adjustment to the opening balance of retained earnings; however, no adjustment was required as a result of adopting the new revenue standard. The comparative information has not been restated and continues to be reported under the historic accounting standards in effect for those periods. The impact of the adoption of the new revenue standard is not expected to be material to the Company’s net income on an ongoing basis. In February 2016, the FASB issued ASU No. 2016-02 , Leases (Topic 842) . The standard supersedes the previous lease guidance by requiring lessees to recognize a right-to-use asset and lease liability on the balance sheet for all leases with lease terms of greater than one year while maintaining substantially similar classifications for financing and operating leases. The guidance is effective for periods after December 15, 2018 , and the Company will not early adopt. The Company expects to apply the transition method permitted by ASU No. 2018-11 , Leases (Topic 842): Targeted Improvements , issued in August 2018, which permits an entity to recognize a cumulative-effect adjustment to the opening balance of retained earnings in the period of adoption with no adjustment made to the comparative periods presented in the consolidated financial statements. The Company also expects to utilize the practical expedient provided by ASU 2018-11 to not separate non-lease components from the associated lease component and, instead, to account for those components as a single component if the non-lease components would be accounted for under ASC 606 and other conditions are met. The Company has identified its portfolio of leased assets under the new standard and is in the process of evaluating the impact of this guidance on its consolidated financial statements and related disclosures. The adoption will increase asset and liability balances on the consolidated balance sheets due to the required recognition of right-of-use assets and corresponding lease liabilities; however, that impact is currently not known. The Company is in the process of designing processes and controls needed to comply with the requirements of the new standard, which includes the implementation of a lease accounting software solution to support lease portfolio management and accounting and disclosures. Additionally, in January 2018 , the FASB issued ASU No. 2018-01 , Leases (Topic 842): Land Easement Practical Expedient for Transition to Topic 842 . The amendments in this update provide an optional expedient to not evaluate existing or expired land easements that were not previously accounted for under current leases guidance in Topic 840. An entity that elects this practical expedient should evaluate new or modified land easements beginning at the date of adoption. The Company does not currently account for any land easements under Topic 840 and plans to utilize this practical expedient in conjunction with the adoption of ASU 2016-02. In June 2016 , the FASB issued ASU No. 2016-13 , Financial Instruments-Credit Losses: Measurement of Credit Losses on Financial Instruments . This ASU amends guidance on reporting credit losses for assets held at amortized cost basis and available for sale debt securities. For assets held at amortized cost basis, this ASU eliminates the probable initial recognition threshold in current GAAP and instead, requires an entity to reflect its current estimate of all expected credit losses. The amendments affect loans, debt securities, trade receivables, net investments in leases, off balance sheet credit exposure, reinsurance receivables and any other financial assets not excluded from the scope that have the contractual right to receive cash. The guidance is effective for periods after December 15, 2019, with early adoption permitted. The Company is currently evaluating the impact this standard will have on its financial statements and related disclosures and does not anticipate it to have a material effect. In August 2016 , the FASB issued ASU No. 2016-15 , Statement of Cash Flows: Classification of Certain Cash Receipts and Cash Payments . This ASU clarifies how certain cash receipts and cash payments should be classified and presented in the statement of cash flows. The Company adopted this standard in the first quarter of 2018 and has made an accounting policy election to classify distributions received from equity method investees using the nature of the distribution approach, which classifies distributions received from investees as either cash inflows from operating activities or cash inflows from investing activities in the statement of cash flows based on the nature of the activities of the investee that generated the distribution. The impact of adopting this ASU was not material to prior periods presented. In November 2016 , the FASB issued ASU No. 2016-18, Statement of Cash Flows (Topic 230): Restricted Cash . This ASU requires that amounts generally described as restricted cash and restricted cash equivalents be included with cash and cash equivalents when reconciling the beginning-of-period and end-of-period amounts shown on the statement of cash flows and to provide a reconciliation of the totals in the statement of cash flows to the related captions in the balance sheet when the cash, cash equivalents, restricted cash, and restricted cash equivalents are presented in more than one line item on the balance sheet. The Company adopted this standard in the first quarter of 2018 using the retrospective transition method. The adoption of this standard had no impact on the statement of cash flows for the nine months ended September 30, 2018 and resulted in the addition of $185.0 million of restricted cash to the beginning cash balance and an increase to net cash used in investing activities by the same amount on the statement of cash flows for the nine months ended September 30, 2017 . In January 2017 , the FASB issued ASU No. 2017-01 , Clarifying the Definition of a Business . Under the current business combination guidance, there are three elements of a business: inputs, processes and outputs. The revised guidance adds an initial screen test to determine if substantially all of the fair value of the gross assets acquired is concentrated in a single asset or group of similar assets. If that screen is met, the set of assets is not a business. The new framework also specifies the minimum required inputs and processes necessary to be a business. The Company adopted this standard in the first quarter of 2018 with no significant effect on its financial statements or related disclosures. In February 2018 , the FASB issued ASU No. 2018-02 , Income statement - Reporting Comprehensive Income (Topic 220) - Reclassification of Certain Tax Effects from Accumulated Other Comprehensive Income , which allows a reclassification from accumulated other comprehensive income to retained earnings for standard tax effects resulting from the Tax Cuts and Jobs Act of 2017. The amendment will be effective for reporting periods beginning after December 15, 2018 , and early adoption is permitted. The Company is currently assessing the impact of the ASU on its consolidated financial statements and related disclosures. In August 2018 , the FASB issued ASU No. 2018-13 , Fair Value Measurement (Topic 820): Disclosure Framework—Changes to the Disclosure Requirements for Fair Value Measurement which removes, modifies, and adds certain disclosure requirements on fair value measurements. The amendment will be effective for reporting periods beginning after December 15, 2019 , and early adoption is permitted. The Company is currently assessing the impact of the ASU on its consolidated financial statements and related disclosures. In August 2018 , the FASB also issued ASU No. 2018-15 , Intangibles—Goodwill and Other—Internal-Use Software (Subtopic 350-40): Customer’s Accounting for Implementation Costs Incurred in a Cloud Computing Arrangement That Is a Service Contract , which aligns the accounting for costs associated with implementing a cloud computing arrangement in a hosting arrangement that is a service contract with the accounting for implementation costs incurred to develop or obtain internal-use software. The amendment will be effective for reporting periods beginning after December 15, 2019 , and early adoption is permitted. The Company is currently assessing the impact of the ASU on its consolidated financial statements and related disclosures.

ACQUISITIONS (Tables)

ACQUISITIONS (Tables)	9 Months Ended
	Sep. 30, 2018
Business Combinations [Abstract]
Schedule of recognized identified assets acquired and liabilities assumed	The following table summarizes the consideration paid by the Company in the Vitruvian Acquisition to acquire the properties and the fair value amount of the assets acquired as of February 17, 2017. (In thousands) Consideration: Cash, net of purchase price adjustments $ 1,354,093 Fair value of Gulfport’s common stock issued 464,639 Total consideration $ 1,818,732 Estimated fair value of identifiable assets acquired and liabilities assumed: Oil and natural gas properties Proved properties $ 362,264 Unproved properties 1,462,957 Asset retirement obligations (6,489 ) Total fair value of net identifiable assets acquired $ 1,818,732
Schedule of pro forma information	The pro forma combined financial information has been included for comparative purposes and is not necessarily indicative of the results that might have actually occurred had the Vitruvian Acquisition taken place on January 1, 2017; furthermore, the financial information is not intended to be a projection of future results. Three months ended Nine months ended September 30, 2017 September 30, 2017 (In thousands, except share data) Pro forma revenue $ 265,498 $ 958,354 Pro forma net income $ 18,235 $ 300,052 Pro forma earnings per share (basic) $ 0.10 $ 1.68 Pro forma earnings per share (diluted) $ 0.10 $ 1.68 For the three months ended September 30, 2017 and the period from the acquisition date of February 17, 2017 to September 30, 2017 , the assets acquired in the Vitruvian Acquisition contributed the following amounts of revenue to the Company's consolidated statements of operations. The amount of net income contributed by the assets is not presented below as it is impracticable to calculate due to the Company integrating the acquired assets into its overall operations using the full cost method of accounting. Period from February 17, 2017 Three months ended to September 30, 2017 September 30, 2017 (In thousands) Revenue $ 60,940 $ 137,706

PROPERTY AND EQUIPMENT (Tables)

PROPERTY AND EQUIPMENT (Tables)	9 Months Ended
	Sep. 30, 2018
Property, Plant and Equipment [Abstract]
Schedule of property and equipment	The major categories of property and equipment and related accumulated depletion, depreciation, amortization and impairment as of September 30, 2018 and December 31, 2017 are as follows: September 30, 2018 December 31, 2017 (In thousands) Oil and natural gas properties $ 9,936,714 $ 9,169,156 Office furniture and fixtures 42,302 37,369 Building 44,565 44,565 Land 5,521 4,820 Total property and equipment 10,029,102 9,255,910 Accumulated depletion, depreciation, amortization and impairment (4,506,306 ) (4,153,733 ) Property and equipment, net $ 5,522,796 $ 5,102,177
Summary of non-producing properties excluded from amortization by area	The following table summarizes the Company’s non-producing properties excluded from amortization by area at September 30, 2018 : September 30, 2018 (In thousands) Utica $ 1,522,633 MidContinent 1,401,392 Niobrara 449 Southern Louisiana 571 Bakken 100 $ 2,925,145
Schedule of asset retirement obligation	A reconciliation of the Company’s asset retirement obligation for the nine months ended September 30, 2018 and 2017 is as follows: September 30, 2018 September 30, 2017 (In thousands) Asset retirement obligation, beginning of period $ 75,100 $ 34,276 Liabilities incurred 1,468 11,557 Liabilities settled (719 ) (2,520 ) Accretion expense 3,056 1,148 Revisions in estimated cash flows (374 ) — Asset retirement obligation as of end of period 78,531 44,461 Less current portion 120 195 Asset retirement obligation, long-term $ 78,411 $ 44,266

EQUITY INVESMENTS (Tables)

EQUITY INVESMENTS (Tables)	9 Months Ended
	Sep. 30, 2018
Equity Method Investments and Joint Ventures [Abstract]
Schedule of equity method investments	Investments accounted for by the equity method consist of the following as of September 30, 2018 and December 31, 2017 : Carrying value (Income) loss from equity method investments Approximate ownership % September 30, 2018 December 31, 2017 Three months ended September 30, Nine months ended September 30, 2018 2017 2018 2017 (In thousands) Investment in Tatex Thailand II, LLC 23.5 % $ — $ — $ (137 ) $ (95 ) $ (241 ) $ (549 ) Investment in Grizzly Oil Sands ULC 24.9999 % 53,381 57,641 275 296 833 869 Investment in Timber Wolf Terminals LLC 50.0 % — 983 — 4 536 8 Investment in Windsor Midstream LLC 22.5 % 39 30 — (2 ) (9 ) 25,232 Investment in Stingray Cementing LLC (1) — % — — — — — 205 Investment in Stingray Energy Services LLC (1) — % — — — — — 282 Investment in Sturgeon Acquisitions LLC (1) — % — — — — — (71 ) Investment in Mammoth Energy Services, Inc. (1) 22.0 % 179,109 165,715 (12,996 ) 2,407 (35,708 ) 4,907 Investment in Strike Force Midstream LLC (2) — % — 77,743 — 127 (693 ) 2,585 $ 232,529 $ 302,112 $ (12,858 ) $ 2,737 $ (35,282 ) $ 33,468 (1) On June 5, 2017, Mammoth Energy Services, Inc. ("Mammoth Energy") acquired Stingray Cementing LLC, Stingray Energy Services LLC and Sturgeon Acquisitions LLC. See below under Mammoth Energy Partners LP/Mammoth Energy Services, Inc. for information regarding these transactions. (2) On May 1, 2018, the Company sold its 25% interest in Strike Force Midstream to EQT Midstream Partners, LP. See below under under Strike Force Midstream LLC for information regarding this transaction.
Summary of equity investments - balance sheet	The tables below summarize financial information for the Company’s equity investments as of September 30, 2018 and December 31, 2017 . Summarized balance sheet information: September 30, 2018 December 31, 2017 (In thousands) Current assets $ 481,394 $ 415,032 Noncurrent assets $ 1,336,604 $ 1,542,090 Current liabilities $ 358,177 $ 261,086 Noncurrent liabilities $ 48,328 $ 148,839
Summary of equity investments - income statement	Summarized results of operations: Three months ended September 30, Nine months ended September 30, 2018 2017 2018 2017 (In thousands) Gross revenue $ 384,043 $ 160,950 $ 1,451,580 $ 357,901 Net income (loss) $ 68,414 $ 2,101 $ 181,884 $ (109,651 )

LONG-TERM DEBT (Tables)

LONG-TERM DEBT (Tables)	9 Months Ended
	Sep. 30, 2018
Long-term Debt, Unclassified [Abstract]
Summary of long-term debt	Long-term debt consisted of the following items as of September 30, 2018 and December 31, 2017 : September 30, 2018 December 31, 2017 (In thousands) Revolving credit agreement (1) $ 60,000 $ — 6.625% senior unsecured notes due 2023 (2) 350,000 350,000 6.000% senior unsecured notes due 2024 (3) 650,000 650,000 6.375% senior unsecured notes due 2025 (4) 600,000 600,000 6.375% senior unsecured notes due 2026 (5) 450,000 450,000 Net unamortized debt issuance costs (6) (31,824 ) (34,781 ) Construction loan (7) 23,296 23,724 Less: current maturities of long term debt (647 ) (622 ) Debt reflected as long term $ 2,100,825 $ 2,038,321 The Company capitalized approximately $1.6 million and $4.0 million in interest expense to undeveloped oil and natural gas properties during the three and nine months ended September 30, 2018 , respectively. The Company capitalized approximately $2.1 million and $8.8 million in interest expense to undeveloped oil and natural gas properties during the three and nine months ended September 30, 2017 , respectively. (1) The Company has entered into a senior secured revolving credit facility, as amended, with The Bank of Nova Scotia, as the lead arranger and administrative agent and certain lenders from time to time party thereto. The credit agreement provides for a maximum facility amount of $1.5 billion and matures on December 31, 2021. On March 29, 2017, the Company further amended its revolving credit facility to, among other things, amend the definition of the term EBITDAX to permit pro forma treatment of acquisitions that involve the payment of consideration by Gulfport and its subsidiaries in excess of $50.0 million and of dispositions of property or series of related dispositions of properties that yields gross proceeds to Gulfport or any of its subsidiaries in excess of $50.0 million . On May 4, 2017, the revolving credit facility was further amended to increase the borrowing base from $700.0 million to $1.0 billion , adjust certain of the Company’s investment baskets and add five additional banks to the syndicate. On November 21, 2017, the Company further amended its revolving credit facility to, among other things, (a) decrease the applicable rate for all loans by 0.5% and (b) add a provision that allows Gulfport to elect a commitment amount (the “Elected Commitment Amount”) that is less than the borrowing base. In connection with this amendment, the borrowing base was set at $1.2 billion , with an elected commitment of $1.0 billion . On May 21, 2018, the Company further amended its revolving credit facility to, among other things, (a) decrease the applicable rate for all loans by 0.25% , (b) permit Gulfport and each of its subsidiaries to use the proceeds from dispositions of certain investments to acquire the common stock or other equity interests of Gulfport, subject to certain limitations and (c) increase the borrowing base to $1.4 billion , with an elected commitment of $1.0 billion . As of September 30, 2018 , $60.0 million was outstanding under the revolving credit facility and the total availability for future borrowings under this facility, after giving effect to an aggregate of $316.2 million of letters of credit, was $623.8 million . The Company’s wholly-owned subsidiaries have guaranteed the obligations of the Company under the revolving credit facility. Advances under the revolving credit facility may be in the form of either base rate loans or eurodollar loans. The interest rate for base rate loans is equal to (1) the applicable rate, which ranges from 0.25% to 1.25% , plus (2) the highest of: (a) the federal funds rate plus 0.50% , (b) the rate of interest in effect for such day as publicly announced from time to time by agent as its “prime rate,” and (c) the eurodollar rate for an interest period of one month plus 1.00% . The interest rate for eurodollar loans is equal to (1) the applicable rate, which ranges from 1.25% to 2.25% , plus (2) the London interbank offered rate that appears on pages LIBOR01 or LIBOR02 of the Reuters screen that displays such rate for deposits in U.S. dollars, or, if such rate is not available, the rate as administered by ICE Benchmark Administration (or any other person that takes over administration of such rate) per annum equal to the offered rate on such other page or service that displays on average London interbank offered rate as determined by ICE Benchmark Administration (or any other person that takes over administration of such rate) for deposits in U.S. dollars, or, if such rate is not available, the average quotations for three major New York money center banks of whom the agent shall inquire as the “London Interbank Offered Rate” for deposits in U.S. dollars. At September 30, 2018 , amounts borrowed under the credit facility bore interest at the eurodollar rate with a weighted average of 3.72% . The revolving credit facility contains customary negative covenants including, but not limited to, restrictions on the Company’s and its subsidiaries’ ability to: • incur indebtedness; • grant liens; • pay dividends and make other restricted payments; • make investments; • make fundamental changes; • enter into swap contracts; • dispose of assets; • change the nature of their business; and • enter into transactions with affiliates. The negative covenants are subject to certain exceptions as specified in the revolving credit facility. The revolving credit facility also contains certain affirmative covenants, including, but not limited to the following financial covenants: (i) the ratio of net funded debt to EBITDAX (net income, excluding (i) any non-cash revenue or expense associated with swap contracts resulting from ASC 815 and (ii) any cash or non-cash revenue or expense attributable to minority investments plus without duplication and, in the case of expenses, to the extent deducted from revenues in determining net income, the sum of (a) the aggregate amount of consolidated interest expense for such period, (b) the aggregate amount of income, franchise, capital or similar tax expense (other than ad valorem taxes) for such period, (c) all amounts attributable to depletion, depreciation, amortization and asset or goodwill impairment or writedown for such period, (d) all other non-cash charges, (e) exploration costs deducted in determining net income under successful efforts accounting, (f) actual cash distributions received from minority investments, (g) to the extent actually reimbursed by insurance, expenses with respect to liability on casualty events or business interruption, and (h) all reasonable transaction expenses related to dispositions and acquisitions of assets, investments and debt and equity offerings (provided that expenses related to any unsuccessful disposition will be limited to $3.0 million in the aggregate) for a twelve-month period may not be greater than 4.00 to 1.00 ; and (ii) the ratio of EBITDAX to interest expense for a twelve-month period may not be less than 3.00 to 1.00 . The Company was in compliance with its financial covenants at September 30, 2018 . (2) On April 21, 2015, the Company issued $350.0 million in aggregate principal amount of 6.625% Senior Notes due 2023 (the “2023 Notes”) to qualified institutional buyers pursuant to Rule 144A under the Securities Act and to certain non-U.S. persons in accordance with Regulation S under the Securities Act (the “2023 Notes Offering”). The Company received net proceeds of approximately $343.6 million after initial purchaser discounts and commissions and estimated offering expenses. The 2023 Notes were issued under an indenture, dated as of April 21, 2015, among the Company, the subsidiary guarantors party thereto and Wells Fargo Bank, National Association, as trustee. In October 2015, the 2023 Notes were exchanged for a new issue of substantially identical debt securities registered under the Securities Act. Pursuant to the indenture relating to the 2023 Notes, interest on the 2023 Notes accrues at a rate of 6.625% per annum on the outstanding principal amount thereof, payable semi-annually on May 1 and November 1 of each year. The 2023 Notes are not guaranteed by Grizzly Holdings, Inc. and will not be guaranteed by any of the Company’s future unrestricted subsidiaries. (3) On October 14, 2016, the Company issued $650.0 million in aggregate principal amount of 6.000% Senior Notes due 2014 (the "2024 Notes"). The 2024 Notes were issued under an indenture, dated as of October 14, 2016, among the Company, the subsidiary guarantors party thereto and the senior note indenture trustee (the “2024 Indenture”), to qualified institutional buyers pursuant to Rule 144A under the Securities Act and to certain non-U.S. persons in accordance with Regulation S under the Securities Act (the “2024 Notes Offering”). Under the 2024 Indenture, interest on the 2024 Notes accrues at a rate of 6.000% per annum on the outstanding principal amount thereof from October 14, 2016, payable semi-annually on April 15 and October 15 of each year, commencing on April 15, 2017. The 2024 Notes will mature on October 15, 2024. The Company received approximately $638.9 million in net proceeds from the offering of the 2024 Notes, which was used, together with cash on hand, to purchase the then outstanding 2020 Notes in a concurrent cash tender offer, to pay fees and expenses thereof, and to redeem any of the 2020 Notes that remained outstanding after the completion of the tender offer. (4) On December 21, 2016, the Company issued $600.0 million in aggregate principal amount of 6.375% Senior Notes due 2025 (the “2025 Notes”). The 2025 Notes were issued under an indenture, dated as of December 21, 2016, among the Company, the subsidiary guarantors party thereto and the senior note indenture trustee (the “2025 Indenture”), to qualified institutional buyers pursuant to Rule 144A under the Securities Act of 1933, and to certain non-U.S. persons in accordance with Regulation S under the Securities Act. Under the 2025 Indenture, interest on the 2025 Notes accrues at a rate of 6.375% per annum on the outstanding principal amount thereof from December 21, 2016, payable semi-annually on May 15 and November 15 of each year, commencing on May 15, 2017. The 2025 Notes will mature on May 15, 2025. The Company received approximately $584.7 million in net proceeds from the offering of the 2025 Notes, which was used, together with the net proceeds from the Company’s December 2016 common stock offering and cash on hand, to fund the cash portion of the purchase price for the Vitruvian Acquisition. See “Note 1 – Acquisitions” for additional discussion of the Vitruvian Acquisition. (5) On October 11, 2017, the Company issued $450.0 million in aggregate principal amount of its 6.375% Senior Notes due 2026 (the “2026 Notes”) to qualified institutional buyers pursuant to Rule 144A under the Securities Act and to certain non-U.S. persons in accordance with Regulation S under the Securities Act. Interest on the 2026 Notes accrues at a rate of 6.375% per annum on the outstanding principal amount thereof from October 11, 2017, payable semi-annually on January 15 and July 15 of each year, commencing on January 15, 2018. The 2026 Notes will mature on January 15, 2026. The Company received approximately $444.1 million in net proceeds from the offering of the 2026 Notes, a portion of which was used to repay all of the Company's outstanding borrowings under its secured revolving credit facility on October 11, 2017 and the balance was used to fund the remaining outspend related to the Company's 2017 capital development plans. In connection with the 2026 Notes offering, the Company and its subsidiary guarantors entered into a registration rights agreement pursuant to which the Company agreed to file a registration statement with respect to an offer to exchange the 2026 Notes for a new issue of substantially identical debt securities registered under the Securities Act. On January 18, 2018, the Company filed a registration statement on Form S-4 with respect to an offer to exchange the 2026 Notes for substantially identical debt securities registered under the Securities Act, which registration statement was declared effective by the SEC on February 12, 2018. The exchange offer relating to the 2026 notes closed on March 22, 2018. (6) Loan issuance costs related to the 2023 Notes, the 2024 Notes, the 2025 Notes and the 2026 Notes (collectively the “Notes”) have been presented as a reduction to the Notes. At September 30, 2018 , total unamortized debt issuance costs were $4.6 million for the 2023 Notes, $9.0 million for the 2024 Notes, $12.9 million for the 2025 Notes and $5.2 million for the 2026 Notes. In addition, loan commitment fee costs for the construction loan agreement described immediately below were $0.1 million at September 30, 2018 . (7) On June 4, 2015, the Company entered into a construction loan agreement (the “Construction Loan”) with InterBank for the construction of a new corporate headquarters in Oklahoma City, which was substantially completed in December 2016. The Construction Loan allows for maximum principal borrowings of $24.5 million and required the Company to fund 30% of the cost of the construction before any funds could be drawn, which occurred in January 2016. Interest accrues daily on the outstanding principal balance at a fixed rate of 4.50% per annum and was payable on the last day of the month through May 31, 2017. Starting June 30, 2017, the Company began making monthly payments of principal and interest, with the final payment due June 4, 2025. At September 30, 2018 , the total borrowings under the Construction Loan were approximately $23.3 million .

STOCK-BASED COMPENSATION (Table

STOCK-BASED COMPENSATION (Tables)	9 Months Ended
	Sep. 30, 2018
Share-based Compensation [Abstract]
Schedule of restricted stock activity	The following table summarizes restricted stock activity for the nine months ended September 30, 2018 : Number of Unvested Restricted Shares Weighted Average Grant Date Fair Value Unvested shares as of January 1, 2018 976,027 $ 18.71 Granted 1,197,628 9.45 Vested (618,202 ) 17.77 Forfeited (32,633 ) 17.31 Unvested shares as of September 30, 2018 1,522,820 $ 11.84

EARNINGS PER SHARE (Tables)

EARNINGS PER SHARE (Tables)	9 Months Ended
	Sep. 30, 2018
Earnings Per Share [Abstract]
Schedule of earnings per share	Reconciliations of the components of basic and diluted net income per common share are presented in the tables below: Three months ended September 30, 2018 2017 Income Shares Per Share Income Shares Per Share (In thousands, except share data) Basic: Net income $ 95,150 173,057,538 $ 0.55 $ 18,235 182,957,416 $ 0.10 Effect of dilutive securities: Stock options and awards — 247,376 — 51,020 Diluted: Net income $ 95,150 173,304,914 $ 0.55 $ 18,235 183,008,436 $ 0.10 Nine months ended September 30, 2018 2017 Income Shares Per Income Shares Per (In thousands, except share data) Basic: Net income $ 296,559 175,776,312 $ 1.69 $ 278,626 178,736,569 $ 1.56 Effect of dilutive securities: Stock options and awards — 664,149 — 394,001 Diluted: Net income $ 296,559 176,440,461 $ 1.68 $ 278,626 179,130,570 $ 1.56

COMMITTMENTS AND CONTINGENCIES

COMMITTMENTS AND CONTINGENCIES (Tables)	9 Months Ended
	Sep. 30, 2018
Long-term Purchase Commitment [Line Items]
Schedule of future minimum lease commitments	Future minimum lease commitments under these leases at September 30, 2018 were as follows: (In thousands) Remaining 2018 $ 39 2019 144 2020 90 2021 38 Total $ 311
Schedule of firm transportation commitments	The table below presents these commitments at September 30, 2018 as follows: (MMBtu per day) Remaining 2018 590,000 2019 659,000 2020 526,000 2021 372,000 2022 272,000 Thereafter 240,000 Total 2,659,000
Transportation commitment
Long-term Purchase Commitment [Line Items]
Schedule of other commitments	The table below presents these commitments at September 30, 2018 as follows: (In thousands) Remaining 2018 $ 62,012 2019 251,644 2020 247,581 2021 246,620 2022 246,620 Thereafter 2,511,853 Total $ 3,566,330

DERIVATIVE INSTRUMENTS (Tables)

DERIVATIVE INSTRUMENTS (Tables)	9 Months Ended
	Sep. 30, 2018
General Discussion of Derivative Instruments and Hedging Activities [Abstract]
Schedule of open fixed price swap positions and natural gas basis swap positions	As of September 30, 2018 , the Company had the following natural gas basis swap positions for Transco Zone 4. Location Daily Volume (MMBtu/day) Weighted Average Price Remaining 2018 Transco Zone 4 40,000 $ (0.05 ) 2019 Transco Zone 4 60,000 $ (0.05 ) 2020 Transco Zone 4 60,000 $ (0.05 ) Below is a summary of the Company’s open fixed price swap positions as of September 30, 2018 . Location Daily Volume (MMBtu/day) Weighted Remaining 2018 NYMEX Henry Hub 1,010,000 $ 3.01 2019 NYMEX Henry Hub 1,154,000 $ 2.81 2020 NYMEX Henry Hub 204,000 $ 2.77 Location Daily Volume Weighted Remaining 2018 ARGUS LLS 2,000 $ 56.22 2019 ARGUS LLS 1,000 $ 59.55 Remaining 2018 NYMEX WTI 4,500 $ 53.72 2019 NYMEX WTI 4,000 $ 58.28 Location Daily Volume Weighted 2019 Mont Belvieu C2 1,000 $ 18.48 Remaining 2018 Mont Belvieu C3 4,000 $ 29.34 2019 Mont Belvieu C3 4,000 $ 28.87 Remaining 2018 Mont Belvieu C5 500 $ 46.62 2019 Mont Belvieu C5 500 $ 54.08 The Company sold call options and used the associated premiums to enhance the fixed price for a portion of the fixed price natural gas swaps listed above. Each short call option has an established ceiling price. When the referenced settlement price is above the price ceiling established by these short call options, the Company pays its counterparty an amount equal to the difference between the referenced settlement price and the price ceiling multiplied by the hedged contract volumes. Location Daily Volume (MMBtu/day) Weighted Average Price October 2018 - March 2019 NYMEX Henry Hub 50,000 $ 3.13 April 2019 - December 2019 NYMEX Henry Hub 30,000 $ 3.10
Schedule of derivative instruments in balance sheet	The following table presents the fair value of the Company’s derivative instruments on a gross basis at September 30, 2018 and December 31, 2017 : September 30, 2018 December 31, 2017 (In thousands) Short-term derivative instruments - asset $ 19,809 $ 78,847 Long-term derivative instruments - asset $ 3,530 $ 8,685 Short-term derivative instruments - liability $ 62,601 $ 32,534 Long-term derivative instruments - liability $ 15,101 $ 2,989
Schedule of net gain (loss) on derivatives	The following table presents the gain and loss recognized in net (loss) gain on natural gas, oil and NGL derivatives in the accompanying consolidated statements of operations for the three and nine months ended September 30, 2018 and 2017 . Net (loss) gain on derivative instruments Three months ended September 30, Nine months ended September 30, 2018 2017 2018 2017 (In thousands) Natural gas derivatives $ 14,101 $ (7,077 ) $ (26,789 ) $ 135,868 Oil derivatives (11,610 ) (6,571 ) (45,176 ) 12,477 Natural gas liquids derivatives (12,154 ) (9,212 ) (24,772 ) (6,757 ) Total $ (9,663 ) $ (22,860 ) $ (96,737 ) $ 141,588
Recognized derivative assets	The following table presents the gross amounts of recognized derivative assets and liabilities in the consolidated balance sheets and the amounts that are subject to offsetting under master netting arrangements with counterparties, all at fair value. As of September 30, 2018 Gross Assets (Liabilities) Gross Amounts Presented in the Subject to Master Net Consolidated Balance Sheets Netting Agreements Amount (In thousands) Derivative assets $ 23,339 $ (17,053 ) $ 6,286 Derivative liabilities $ (77,702 ) $ 17,053 $ (60,649 ) As of December 31, 2017 Gross Assets (Liabilities) Gross Amounts Presented in the Subject to Master Net Consolidated Balance Sheets Netting Agreements Amount (In thousands) Derivative assets $ 87,532 $ (22,199 ) $ 65,333 Derivative liabilities $ (35,523 ) $ 22,199 $ (13,324 )
Recognized derivative liabilities	The following table presents the gross amounts of recognized derivative assets and liabilities in the consolidated balance sheets and the amounts that are subject to offsetting under master netting arrangements with counterparties, all at fair value. As of September 30, 2018 Gross Assets (Liabilities) Gross Amounts Presented in the Subject to Master Net Consolidated Balance Sheets Netting Agreements Amount (In thousands) Derivative assets $ 23,339 $ (17,053 ) $ 6,286 Derivative liabilities $ (77,702 ) $ 17,053 $ (60,649 ) As of December 31, 2017 Gross Assets (Liabilities) Gross Amounts Presented in the Subject to Master Net Consolidated Balance Sheets Netting Agreements Amount (In thousands) Derivative assets $ 87,532 $ (22,199 ) $ 65,333 Derivative liabilities $ (35,523 ) $ 22,199 $ (13,324 )

FAIR VALUE MEASUREMENTS (Tables

FAIR VALUE MEASUREMENTS (Tables)	9 Months Ended
	Sep. 30, 2018
Fair Value Disclosures [Abstract]
Summary of financial and non-financial assets and liabilities by valuation level	The following tables summarize the Company’s financial and non-financial assets and liabilities by ASC 820 valuation level as of September 30, 2018 and December 31, 2017 : September 30, 2018 Level 1 Level 2 Level 3 (In thousands) Assets: Derivative Instruments $ — $ 23,339 $ — Liabilities: Derivative Instruments $ — $ 77,702 $ — December 31, 2017 Level 1 Level 2 Level 3 (In thousands) Assets: Derivative Instruments $ — $ 87,532 $ — Liabilities: Derivative Instruments $ — $ 35,523 $ —

CONDENSED CONSOLIDATING FINAN_2

CONDENSED CONSOLIDATING FINANCIAL INFORMATION (Tables)	9 Months Ended
	Sep. 30, 2018
Condensed Financial Information Disclosure [Abstract]
CONDENSED CONSOLIDATING BALANCE SHEETS	CONDENSED CONSOLIDATING BALANCE SHEETS (Amounts in thousands) September 30, 2018 Parent Guarantors Non-Guarantor Eliminations Consolidated Assets Current assets: Cash and cash equivalents $ 89,214 $ 35,357 $ — $ — $ 124,571 Accounts receivable - oil and natural gas sales 111,463 45,928 — — 157,391 Accounts receivable - joint interest and other 19,066 20,445 — — 39,511 Accounts receivable - related parties 79 — — — 79 Accounts receivable - intercompany 662,319 240,373 — (902,692 ) — Prepaid expenses and other current assets 7,521 2,221 — — 9,742 Short-term derivative instruments 19,809 — — — 19,809 Total current assets 909,471 344,324 — (902,692 ) 351,103 Property and equipment: Oil and natural gas properties, full-cost accounting 7,003,396 2,934,047 — (729 ) 9,936,714 Other property and equipment 91,637 751 — — 92,388 Accumulated depletion, depreciation, amortization and impairment (4,506,267 ) (39 ) — — (4,506,306 ) Property and equipment, net 2,588,766 2,934,759 — (729 ) 5,522,796 Other assets: Equity investments and investments in subsidiaries 2,723,140 — 53,380 (2,543,991 ) 232,529 Long-term derivative instruments 3,530 — — — 3,530 Inventories 6,800 1,434 — — 8,234 Other assets 13,018 4,020 — — 17,038 Total other assets 2,746,488 5,454 53,380 (2,543,991 ) 261,331 Total assets $ 6,244,725 $ 3,284,537 $ 53,380 $ (3,447,412 ) $ 6,135,230 Liabilities and Stockholders ’ Equity Current liabilities: Accounts payable and accrued liabilities $ 464,426 $ 118,038 $ — $ — $ 582,464 Accounts payable - intercompany 240,310 662,254 128 (902,692 ) — Asset retirement obligation - current 120 — — — 120 Short-term derivative instruments 62,601 — — — 62,601 Current maturities of long-term debt 647 — — — 647 Total current liabilities 768,104 780,292 128 (902,692 ) 645,832 Long-term derivative instruments 15,101 — — — 15,101 Asset retirement obligation - long-term 65,634 12,777 — — 78,411 Deferred tax liability 3,046 — — — 3,046 Long-term debt, net of current maturities 2,100,825 — — — 2,100,825 Total liabilities 2,952,710 793,069 128 (902,692 ) 2,843,215 Stockholders’ equity: Common stock 1,732 — — — 1,732 Paid-in capital 4,316,006 1,915,598 261,626 (2,177,224 ) 4,316,006 Accumulated other comprehensive (loss) income (46,354 ) — (44,338 ) 44,338 (46,354 ) Retained (deficit) earnings (979,369 ) 575,870 (164,036 ) (411,834 ) (979,369 ) Total stockholders’ equity 3,292,015 2,491,468 53,252 (2,544,720 ) 3,292,015 Total liabilities and stockholders ’ equity $ 6,244,725 $ 3,284,537 $ 53,380 $ (3,447,412 ) $ 6,135,230 CONDENSED CONSOLIDATING BALANCE SHEETS (Amounts in thousands) December 31, 2017 Parent Guarantors Non-Guarantor Eliminations Consolidated Assets Current assets: Cash and cash equivalents $ 67,908 $ 31,649 $ — $ — $ 99,557 Accounts receivable - oil and natural gas sales 112,686 34,087 — — 146,773 Accounts receivable - joint interest and other 15,435 20,005 — — 35,440 Accounts receivable - intercompany 554,439 63,374 — (617,813 ) — Prepaid expenses and other current assets 4,719 193 — — 4,912 Short-term derivative instruments 78,847 — — — 78,847 Total current assets 834,034 149,308 — (617,813 ) 365,529 Property and equipment: Oil and natural gas properties, full-cost accounting, 6,562,147 2,607,738 — (729 ) 9,169,156 Other property and equipment 86,711 43 — — 86,754 Accumulated depletion, depreciation, amortization and impairment (4,153,696 ) (37 ) — — (4,153,733 ) Property and equipment, net 2,495,162 2,607,744 — (729 ) 5,102,177 Other assets: Equity investments and investments in subsidiaries 2,361,575 77,744 57,641 (2,194,848 ) 302,112 Long-term derivative instruments 8,685 — — — 8,685 Deferred tax asset 1,208 — — — 1,208 Inventories 5,816 2,411 — — 8,227 Other assets 12,483 7,331 — — 19,814 Total other assets 2,389,767 87,486 57,641 (2,194,848 ) 340,046 Total assets $ 5,718,963 $ 2,844,538 $ 57,641 $ (2,813,390 ) $ 5,807,752 Liabilities and Stockholders ’ Equity Current liabilities: Accounts payable and accrued liabilities $ 416,249 $ 137,361 $ — $ (1 ) $ 553,609 Accounts payable - intercompany 63,373 554,313 127 (617,813 ) — Asset retirement obligation - current 120 — — — 120 Short-term derivative instruments 32,534 — — — 32,534 Current maturities of long-term debt 622 — — — 622 Total current liabilities 512,898 691,674 127 (617,814 ) 586,885 Long-term derivative instruments 2,989 — — — 2,989 Asset retirement obligation - long-term 63,141 11,839 — — 74,980 Other non-current liabilities — 2,963 — — 2,963 Long-term debt, net of current maturities 2,038,321 — — — 2,038,321 Total liabilities 2,617,349 706,476 127 (617,814 ) 2,706,138 Stockholders’ equity: Common stock 1,831 — — — 1,831 Paid-in capital 4,416,250 1,915,598 259,307 (2,174,905 ) 4,416,250 Accumulated other comprehensive (loss) income (40,539 ) — (38,593 ) 38,593 (40,539 ) Retained (deficit) earnings (1,275,928 ) 222,464 (163,200 ) (59,264 ) (1,275,928 ) Total stockholders’ equity 3,101,614 2,138,062 57,514 (2,195,576 ) 3,101,614 Total liabilities and stockholders ’ equity $ 5,718,963 $ 2,844,538 $ 57,641 $ (2,813,390 ) $ 5,807,752
CONDENSED CONSOLIDATING STATEMENTS OF OPERATIONS	CONDENSED CONSOLIDATING STATEMENTS OF OPERATIONS (Amounts in thousands) Three months ended September 30, 2018 Parent Guarantors Non-Guarantor Eliminations Consolidated Total revenues $ 235,683 $ 125,279 $ — $ — $ 360,962 Costs and expenses: Lease operating expenses 16,502 5,823 — — 22,325 Production taxes 4,505 4,843 — — 9,348 Midstream gathering and processing 54,397 24,516 — — 78,913 Depreciation, depletion and amortization 119,914 1 — — 119,915 General and administrative 16,314 (467 ) 1 — 15,848 Accretion expense 812 225 — — 1,037 212,444 34,941 1 — 247,386 INCOME (LOSS) FROM OPERATIONS 23,239 90,338 (1 ) — 113,576 OTHER (INCOME) EXPENSE: Interest expense 34,254 (1,001 ) — — 33,253 Interest income (86 ) (6 ) — — (92 ) Litigation settlement 917 — — — 917 Gain on sale of equity method investments (2,733 ) — — — (2,733 ) (Income) loss from equity method investments and investments in subsidiaries (104,226 ) (1 ) 275 91,094 (12,858 ) Other income (37 ) (24 ) — — (61 ) (71,911 ) (1,032 ) 275 91,094 18,426 INCOME (LOSS) BEFORE INCOME TAXES 95,150 91,370 (276 ) (91,094 ) 95,150 INCOME TAX BENEFIT — — — — — NET INCOME (LOSS) $ 95,150 $ 91,370 $ (276 ) $ (91,094 ) $ 95,150 CONDENSED CONSOLIDATING STATEMENTS OF OPERATIONS (Amounts in thousands) Three months ended September 30, 2017 Parent Guarantors Non-Guarantor Eliminations Consolidated Total revenues $ 188,390 $ 77,108 $ — $ — $ 265,498 Costs and expenses: Lease operating expenses 16,019 4,001 — — 20,020 Production taxes 4,052 1,367 — — 5,419 Midstream gathering and processing 52,725 16,647 — — 69,372 Depreciation, depletion and amortization 106,649 1 — — 106,650 General and administrative 13,956 (892 ) 1 — 13,065 Accretion expense 335 121 — — 456 Acquisition expense (5 ) 38 — — 33 193,731 21,283 1 — 215,015 (LOSS) INCOME FROM OPERATIONS (5,341 ) 55,825 (1 ) — 50,483 OTHER (INCOME) EXPENSE: Interest expense 27,914 (784 ) — — 27,130 Interest income (29 ) (8 ) — — (37 ) (Income) loss from equity method investments and investments in subsidiaries (53,880 ) 128 296 56,193 2,737 Other income (344 ) (1 ) — — (345 ) (26,339 ) (665 ) 296 56,193 29,485 INCOME (LOSS) BEFORE INCOME TAXES 20,998 56,490 (297 ) (56,193 ) 20,998 INCOME TAX EXPENSE 2,763 — — — 2,763 NET INCOME (LOSS) $ 18,235 $ 56,490 $ (297 ) $ (56,193 ) $ 18,235 CONDENSED CONSOLIDATING STATEMENTS OF OPERATIONS (Amounts in thousands) Nine months ended September 30, 2018 Parent Guarantors Non-Guarantor Eliminations Consolidated Total revenues $ 596,018 $ 343,076 $ — $ — $ 939,094 Costs and expenses: Lease operating expenses 46,926 17,217 — — 64,143 Production taxes 13,309 10,552 — — 23,861 Midstream gathering and processing 152,605 61,941 — — 214,546 Depreciation, depletion, and amortization 352,846 2 — — 352,848 General and administrative 45,100 (2,148 ) 3 — 42,955 Accretion expense 2,397 659 — — 3,056 613,183 88,223 3 — 701,409 (LOSS) INCOME FROM OPERATIONS (17,165 ) 254,853 (3 ) — 237,685 OTHER (INCOME) EXPENSE: Interest expense 103,310 (2,388 ) — — 100,922 Interest income (144 ) (18 ) — — (162 ) Litigation settlement 917 — — — 917 Insurance proceeds (231 ) — — — (231 ) Gain on sale of equity method investments (28,349 ) (96,419 ) — — (124,768 ) (Income) loss from equity method investments and investments in subsidiaries (387,991 ) (694 ) 833 352,570 (35,282 ) Other (income) expense (1,167 ) (34 ) — 1,000 (201 ) (313,655 ) (99,553 ) 833 353,570 (58,805 ) INCOME (LOSS) BEFORE INCOME TAXES 296,490 354,406 (836 ) (353,570 ) 296,490 INCOME TAX BENEFIT (69 ) — — — (69 ) NET INCOME (LOSS) $ 296,559 $ 354,406 $ (836 ) $ (353,570 ) $ 296,559 CONDENSED CONSOLIDATING STATEMENTS OF OPERATIONS (Amounts in thousands) Nine months ended September 30, 2017 Parent Guarantors Non-Guarantor Eliminations Consolidated Total revenues $ 710,184 $ 212,271 $ — $ — $ 922,455 Costs and expenses: Lease operating expenses 49,891 10,153 — — 60,044 Production taxes 10,799 3,665 — — 14,464 Midstream gathering and processing 132,740 43,518 — — 176,258 Depreciation, depletion, and amortization 254,884 3 — — 254,887 General and administrative 39,882 (1,963 ) 3 — 37,922 Accretion expense 908 240 — — 1,148 Acquisition expense — 2,391 — — 2,391 489,104 58,007 3 — 547,114 INCOME (LOSS) FROM OPERATIONS 221,080 154,264 (3 ) — 375,341 OTHER (INCOME) EXPENSE: Interest expense 79,095 (4,298 ) — — 74,797 Interest income (913 ) (14 ) — — (927 ) Gain on sale of equity method investments (12,523 ) — — — (12,523 ) (Income) loss from equity method investments and investments in subsidiaries (124,446 ) 2,586 869 154,459 33,468 Other (income) expense (1,522 ) (241 ) — 900 (863 ) (60,309 ) (1,967 ) 869 155,359 93,952 INCOME (LOSS) BEFORE INCOME TAXES 281,389 156,231 (872 ) (155,359 ) 281,389 INCOME TAX EXPENSE 2,763 — — — 2,763 NET INCOME (LOSS) $ 278,626 $ 156,231 $ (872 ) $ (155,359 ) $ 278,626
CONDENSED CONSOLIDATING STATEMENTS OF COMPREHENSIVE INCOME (LOSS)	CONDENSED CONSOLIDATING STATEMENTS OF COMPREHENSIVE INCOME (LOSS) (Amounts in thousands) Three months ended September 30, 2018 Parent Guarantors Non-Guarantor Eliminations Consolidated Net income (loss) $ 95,150 $ 91,370 $ (276 ) $ (91,094 ) $ 95,150 Foreign currency translation adjustment 3,052 103 2,949 (3,052 ) 3,052 Other comprehensive income (loss) 3,052 103 2,949 (3,052 ) 3,052 Comprehensive income (loss) $ 98,202 $ 91,473 $ 2,673 $ (94,146 ) $ 98,202 Three months ended September 30, 2017 Parent Guarantors Non-Guarantor Eliminations Consolidated Net income (loss) $ 18,235 $ 56,490 $ (297 ) $ (56,193 ) $ 18,235 Foreign currency translation adjustment 6,832 158 6,674 (6,832 ) 6,832 Other comprehensive income (loss) 6,832 158 6,674 (6,832 ) 6,832 Comprehensive income (loss) $ 25,067 $ 56,648 $ 6,377 $ (63,025 ) $ 25,067 Nine months ended September 30, 2018 Parent Guarantors Non-Guarantor Eliminations Consolidated Net income (loss) $ 296,559 $ 354,406 $ (836 ) $ (353,570 ) $ 296,559 Foreign currency translation adjustment (5,815 ) (70 ) (5,745 ) 5,815 (5,815 ) Other comprehensive (loss) income (5,815 ) (70 ) (5,745 ) 5,815 (5,815 ) Comprehensive income (loss) $ 290,744 $ 354,336 $ (6,581 ) $ (347,755 ) $ 290,744 Nine months ended September 30, 2017 Parent Guarantors Non-Guarantor Eliminations Consolidated Net income (loss) $ 278,626 $ 156,231 $ (872 ) $ (155,359 ) $ 278,626 Foreign currency translation adjustment 12,719 232 12,487 (12,719 ) 12,719 Other comprehensive income (loss) 12,719 232 12,487 (12,719 ) 12,719 Comprehensive income (loss) $ 291,345 $ 156,463 $ 11,615 $ (168,078 ) $ 291,345
CONDENSED CONSOLIDATING STATEMENTS OF CASH FLOWS	CONDENSED CONSOLIDATING STATEMENTS OF CASH FLOWS (Amounts in thousands) Nine months ended September 30, 2018 Parent Guarantors Non-Guarantor Eliminations Consolidated Net cash provided by (used in) operating activities $ 416,833 $ 192,123 $ (1 ) $ 1 $ 608,956 Net cash (used in) provided by investing activities (344,330 ) (188,415 ) (2,318 ) 2,318 (532,745 ) Net cash (used in) provided by financing activities (51,197 ) — 2,319 (2,319 ) (51,197 ) Net increase in cash, cash equivalents and restricted cash 21,306 3,708 — — 25,014 Cash, cash equivalents and restricted cash at beginning of period 67,908 31,649 — — 99,557 Cash, cash equivalents and restricted cash at end of period $ 89,214 $ 35,357 $ — $ — $ 124,571 Nine months ended September 30, 2017 Parent Guarantors Non-Guarantor Eliminations Consolidated Net cash provided by (used in) operating activities $ 310,624 $ 181,108 $ (1 ) $ 2 $ 491,733 Net cash (used in) provided by investing activities (2,034,554 ) (1,554,063 ) (1,843 ) 1,408,980 (2,181,480 ) Net cash provided by (used in) financing activities 354,143 1,407,137 1,845 (1,408,982 ) 354,143 Net (decrease) increase in cash, cash equivalents and restricted cash (1,369,787 ) 34,182 1 — (1,335,604 ) Cash, cash equivalents and restricted cash at beginning of period 1,458,882 1,993 — — 1,460,875 Cash, cash equivalents and restricted cash at end of period $ 89,095 $ 36,175 $ 1 $ — $ 125,271

ACQUISITIONS (Narrative) (Detai

ACQUISITIONS (Narrative) (Details) $ / shares in Units, shares in Millions	Feb. 17, 2017USD ($)a$ / sharesshares	Feb. 16, 2017USD ($)	Sep. 30, 2018USD ($)	Sep. 30, 2017USD ($)	Sep. 30, 2017USD ($)	Sep. 30, 2018USD ($)	Sep. 30, 2017USD ($)	Dec. 15, 2016$ / shares
Business Acquisition [Line Items]
Acquisition costs			$ 0	$ 33,000		$ 0	$ 2,391,000
Common stock share price (in usd per share) | $ / shares	$ 19.48							$ 20.96
Vitruvian acquisition
Business Acquisition [Line Items]
Net surface area (in acres) | a	46,400
Total initial purchase price	$ 1,850,000,000
Payments to acquire businesses	$ 1,354,093,000
Equity interest issued or issuable, number of shares (in shares) | shares	23.9
Acquisition costs			$ 0	30,000		$ 0	$ 2,400,000
Goodwill	$ 0
Bargain purchase gain	$ 0
Initial purchase share price (in usd per share) | $ / shares								$ 20.96
Decrease in fair value of shares issued for acquisition, amount		$ 35,300,000
Revenue				$ 60,940,000	$ 137,706,000
Vitruvian acquisition | Indemnity escrow
Business Acquisition [Line Items]
Equity interest issued or issuable, number of shares (in shares) | shares	5.2

ACQUISITIONS (Allocation of Pur

ACQUISITIONS (Allocation of Purchase Price) (Details) - Vitruvian acquisition $ in Thousands	Feb. 17, 2017USD ($)
Business Acquisition [Line Items]
Cash, net of purchase price adjustments	$ 1,354,093
Fair value of Gulfport’s common stock issued	464,639
Total consideration	1,818,732
Asset retirement obligations	(6,489)
Total fair value of net identifiable assets acquired	1,818,732
Proved properties
Business Acquisition [Line Items]
Oil and natural gas properties	362,264
Unproved properties
Business Acquisition [Line Items]
Oil and natural gas properties	$ 1,462,957

ACQUISITIONS (Post-Acquisition

ACQUISITIONS (Post-Acquisition Operating Results) (Details) - USD ($) $ in Thousands	3 Months Ended	7 Months Ended
	Sep. 30, 2017	Sep. 30, 2017
Vitruvian acquisition
Business Acquisition, Pro Forma Information, Nonrecurring Adjustment [Line Items]
Revenue	$ 60,940	$ 137,706

ACQUISITIONS (Pro Forma) (Detai

ACQUISITIONS (Pro Forma) (Details) - Vitruvian acquisition - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended	9 Months Ended
	Sep. 30, 2017	Sep. 30, 2017
Business Acquisition, Pro Forma Information, Nonrecurring Adjustment [Line Items]
Pro forma revenue	$ 265,498	$ 958,354
Pro forma net income	$ 18,235	$ 300,052
Pro forma earnings per share (basic) (in usd per share)	$ 0.10	$ 1.68
Pro forma earnings per share (diluted) (in usd per share)	$ 0.10	$ 1.68

PROPERTY AND EQUIPMENT (Schedul

PROPERTY AND EQUIPMENT (Schedule of Property and Equipment) (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Property, Plant and Equipment [Abstract]
Oil and natural gas properties	$ 9,936,714	$ 9,169,156
Office furniture and fixtures	42,302	37,369
Building	44,565	44,565
Land	5,521	4,820
Total property and equipment	10,029,102	9,255,910
Accumulated depletion, depreciation, amortization and impairment	(4,506,306)	(4,153,733)
Property and equipment, net	$ 5,522,796	$ 5,102,177

PROPERTY AND EQUIPMENT (Narrati

PROPERTY AND EQUIPMENT (Narrative) (Details)	3 Months Ended		9 Months Ended
	Sep. 30, 2018USD ($)	Sep. 30, 2017USD ($)	Sep. 30, 2018USD ($)usd_per_mcf	Sep. 30, 2017USD ($)usd_per_mcf	Dec. 31, 2017USD ($)
Property, Plant and Equipment [Line Items]
Impairment of oil and gas properties			$ 0	$ 0
Cumulative capitalization of general and administrative costs incurred and capitalized to the full cost pool	$ 194,400,000		194,400,000
Capitalized general and administrative costs	10,600,000	$ 8,900,000	$ 28,800,000	$ 25,600,000
Depletion per Mcfe of gas equivalent (usd per Mcfe) | usd_per_mcf			0.94	0.89
Capitalized costs of oil and natural gas properties excluded from amortization	$ 2,925,145,000		$ 2,925,145,000		$ 2,912,974,000
Non-producing leases, extension term	5 years		5 years
Minimum
Property, Plant and Equipment [Line Items]
Expected number of years amortization will commence			3 years
Maximum
Property, Plant and Equipment [Line Items]
Expected number of years amortization will commence			5 years

PROPERTY AND EQUIPMENT (Summary

PROPERTY AND EQUIPMENT (Summary of Non-producing Properties Excluded from Amortization by Area) (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Capitalized Costs of Unproved Properties Excluded from Amortization [Line Items]
Total non-producing properties not subject to amortization	$ 2,925,145	$ 2,912,974
Utica
Capitalized Costs of Unproved Properties Excluded from Amortization [Line Items]
Total non-producing properties not subject to amortization	1,522,633
MidContinent
Capitalized Costs of Unproved Properties Excluded from Amortization [Line Items]
Total non-producing properties not subject to amortization	1,401,392
Niobrara
Capitalized Costs of Unproved Properties Excluded from Amortization [Line Items]
Total non-producing properties not subject to amortization	449
Southern Louisiana
Capitalized Costs of Unproved Properties Excluded from Amortization [Line Items]
Total non-producing properties not subject to amortization	571
Bakken
Capitalized Costs of Unproved Properties Excluded from Amortization [Line Items]
Total non-producing properties not subject to amortization	$ 100

PROPERTY AND EQUIPMENT (Sched_2

PROPERTY AND EQUIPMENT (Schedule of Asset Retirement Obligation) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017
Asset Retirement Obligation, Roll Forward Analysis [Roll Forward]
Asset retirement obligation, beginning of period			$ 75,100	$ 34,276
Liabilities incurred			1,468	11,557
Liabilities settled			(719)	(2,520)
Accretion expense	$ 1,037	$ 456	3,056	1,148
Revisions in estimated cash flows			(374)	0
Asset retirement obligation as of end of period	78,531	44,461	78,531	44,461
Less current portion	120	195	120	195	$ 120
Asset retirement obligation, long-term	$ 78,411	$ 44,266	$ 78,411	$ 44,266	$ 74,980

EQUITY INVESMENTS (Investments

EQUITY INVESMENTS (Investments Accounted for by the Equity Method) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	May 01, 2018	Dec. 31, 2017	Dec. 31, 2014
Schedule of Equity Method Investments [Line Items]
Equity investments and investments in subsidiaries	$ 232,529		$ 232,529			$ 302,112
(Income) loss from equity method investments, net	$ (12,858)	$ 2,737	$ (35,282)	$ 33,468
Investment in Tatex Thailand II, LLC
Schedule of Equity Method Investments [Line Items]
Approximate ownership %	23.50%		23.50%
Equity investments and investments in subsidiaries	$ 0		$ 0			0
(Income) loss from equity method investments, net	$ (137)	(95)	$ (241)	(549)
Investment in Grizzly Oil Sands ULC
Schedule of Equity Method Investments [Line Items]
Approximate ownership %	24.9999%		24.9999%
Equity investments and investments in subsidiaries	$ 53,381		$ 53,381			57,641
(Income) loss from equity method investments, net	$ 275	296	$ 833	869
Investment in Timber Wolf Terminals LLC
Schedule of Equity Method Investments [Line Items]
Approximate ownership %	50.00%		50.00%
Equity investments and investments in subsidiaries	$ 0		$ 0			983
(Income) loss from equity method investments, net	$ 0	4	$ 536	8
Investment in Windsor Midstream LLC
Schedule of Equity Method Investments [Line Items]
Approximate ownership %	22.50%		22.50%
Equity investments and investments in subsidiaries	$ 39		$ 39			30
(Income) loss from equity method investments, net	$ 0	(2)	$ (9)	25,232
Investment in Stingray Cementing LLC
Schedule of Equity Method Investments [Line Items]
Approximate ownership %	0.00%		0.00%
Equity investments and investments in subsidiaries	$ 0		$ 0			0
(Income) loss from equity method investments, net	$ 0	0	$ 0	205
Investment in Stingray Energy Services LLC
Schedule of Equity Method Investments [Line Items]
Approximate ownership %	0.00%		0.00%
Equity investments and investments in subsidiaries	$ 0		$ 0			0
(Income) loss from equity method investments, net	$ 0	0	$ 0	282
Investment in Sturgeon Acquisitions LLC
Schedule of Equity Method Investments [Line Items]
Approximate ownership %	0.00%		0.00%				25.00%
Equity investments and investments in subsidiaries	$ 0		$ 0			0
(Income) loss from equity method investments, net	$ 0	0	$ 0	(71)
Investment in Mammoth Energy Services, Inc.
Schedule of Equity Method Investments [Line Items]
Approximate ownership %	22.00%		22.00%
Equity investments and investments in subsidiaries	$ 179,109		$ 179,109			165,715
(Income) loss from equity method investments, net	$ (12,996)	2,407	$ (35,708)	4,907
Investment in Strike Force Midstream LLC
Schedule of Equity Method Investments [Line Items]
Approximate ownership %	0.00%		0.00%		25.00%
Equity investments and investments in subsidiaries	$ 0		$ 0			$ 77,743
(Income) loss from equity method investments, net	$ 0	$ 127	$ (693)	$ 2,585

EQUITY INVESMENTS (Equity Inves

EQUITY INVESMENTS (Equity Investments Balance Sheet Disclosure) (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Equity Method Investments and Joint Ventures [Abstract]
Current assets	$ 481,394	$ 415,032
Noncurrent assets	1,336,604	1,542,090
Current liabilities	358,177	261,086
Noncurrent liabilities	$ 48,328	$ 148,839

EQUITY INVESMENTS (Equity Inv_2

EQUITY INVESMENTS (Equity Investment Income Statement Disclosure) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Equity Method Investments and Joint Ventures [Abstract]
Gross revenue	$ 384,043	$ 160,950	$ 1,451,580	$ 357,901
Net income (loss)	$ 68,414	$ 2,101	$ 181,884	$ (109,651)

EQUITY INVESMENTS (Narrative) (

EQUITY INVESMENTS (Narrative) (Details) $ / shares in Units, a in Thousands	Jul. 26, 2018USD ($)shares	Jun. 29, 2018USD ($)shares	May 01, 2018USD ($)	Dec. 31, 2017USD ($)	Sep. 30, 2018USD ($)	Sep. 30, 2017USD ($)	Jun. 30, 2017USD ($)	Dec. 31, 2014entity	Sep. 30, 2018USD ($)aproject$ / shares	Sep. 30, 2017USD ($)	Dec. 31, 2014a	Jun. 05, 2017$ / sharesshares	Feb. 17, 2017$ / shares	Dec. 15, 2016$ / shares	Apr. 30, 2015bbl	Jun. 30, 2014bbl
Schedule of Equity Method Investments [Line Items]
(Income) loss from equity method investments, net					$ (12,858,000)	$ 2,737,000			$ (35,282,000)	$ 33,468,000
Distributions from equity method investments									446,000	4,114,000
Share price (in usd per share) | $ / shares													$ 19.48	$ 20.96
Gain on sale of equity method investments					2,733,000	0			124,768,000	12,523,000
Proceeds from sale of equity method investments									226,487,000	0
Payments for equity method investments									2,318,000	44,844,000
Mammoth Energy Services LP
Schedule of Equity Method Investments [Line Items]
Distributions from equity method investments									1,200,000
Equity method investment, ownership interest, percent	22.00%
Shares owned (in shares) | shares	9,829,548
Gain (loss) on disposition of stock from equity method investee					2,700,000				$ 28,300,000
Share dividend (in usd per share) | $ / shares									$ 0.125
Tatex Thailand II, LLC
Schedule of Equity Method Investments [Line Items]
(Income) loss from equity method investments, net					$ (137,000)	(95,000)			$ (241,000)	(549,000)
Equity method investment, ownership interest, percent					23.50%				23.50%
Tatex Thailand III LLC
Schedule of Equity Method Investments [Line Items]
Distributions from equity method investments				$ 200,000
Grizzly Oil Sands ULC
Schedule of Equity Method Investments [Line Items]
Gas and oil area, reserve (in acres) | a									830
(Income) loss from equity method investments, net					$ 275,000	296,000			$ 833,000	869,000
Number of oil sand projects | project									3
Production volume (in bbls/day) | bbl															2,200	11,300
Other than temporary impairment loss									$ 0	0
Equity method investment, amount of cash calls, based on proportionate ownership interest									2,300,000
Equity method investments, increase (decrease) due to foreign currency translation adjustment					$ 2,900,000	6,700,000			$ (5,700,000)	12,500,000
Equity method investment, ownership interest, percent					24.9999%				24.9999%
Timber Wolf Terminals LLC
Schedule of Equity Method Investments [Line Items]
(Income) loss from equity method investments, net					$ 0	4,000			$ 536,000	8,000
Distributions from equity method investments									$ 400,000
Equity method investment, ownership interest, percent					50.00%				50.00%
Windsor Midstream LLC
Schedule of Equity Method Investments [Line Items]
(Income) loss from equity method investments, net					$ 0	(2,000)			$ (9,000)	25,232,000
Distributions from equity method investments									$ 0	500,000
Equity method investment, ownership interest, percent					22.50%				22.50%
Sturgeon Acquisitions LLC
Schedule of Equity Method Investments [Line Items]
(Income) loss from equity method investments, net					$ 0	0			$ 0	(71,000)
Equity method investment, ownership interest, percent					0.00%			25.00%	0.00%		25.00%
Gain on sale of equity method investments							$ 12,500,000
Mammoth Energy Services LP
Schedule of Equity Method Investments [Line Items]
Equity method investments, increase (decrease) due to foreign currency translation adjustment					$ 100,000	160,000			$ (200,000)	230,000
Equity method investment, ownership interest, percent								30.50%			30.50%
Number of entities contributed for ownership interest (in entities) | entity								4
Shares received from equity method investee in exchange for ownership interest (in shares) | shares												2,000,000
Share price (in usd per share) | $ / shares												$ 18.50
Strike Force Midstream LLC
Schedule of Equity Method Investments [Line Items]
(Income) loss from equity method investments, net					$ 0	$ 127,000			(693,000)	2,585,000
Distributions from equity method investments			$ 175,000,000						$ 800,000	3,600,000
Equity method investment, ownership interest, percent			25.00%		0.00%				0.00%
Gain on sale of equity method investments			$ 96,400,000
Payments for equity method investments										$ 43,000,000
Over-allotment option | Mammoth Energy Services LP
Schedule of Equity Method Investments [Line Items]
Proceeds from sale of equity method investments	$ 4,500,000	$ 47,000,000
Over-allotment option | Common Stock | Mammoth Energy Services LP
Schedule of Equity Method Investments [Line Items]
Number of shares sold (in shares) | shares	118,974	1,235,600
Phu Horm Field | Apico Llc
Schedule of Equity Method Investments [Line Items]
Gas and oil area, reserve (in acres) | a									180
Concession Acreage in Southeast Asia | Tatex Thailand III LLC
Schedule of Equity Method Investments [Line Items]
Gas and oil area, reserve (in acres) | a											245
Apico Llc | Tatex Thailand II, LLC
Schedule of Equity Method Investments [Line Items]
Ownership percentage					8.50%				8.50%
Strike Force Midstream LLC | Rice Energy Inc
Schedule of Equity Method Investments [Line Items]
Ownership percentage by parent				75.00%

LONG-TERM DEBT (Break-Down of L

LONG-TERM DEBT (Break-Down of Long-Term Debt) (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017	Oct. 11, 2017	Dec. 21, 2016	Oct. 14, 2016	Jun. 04, 2015	Apr. 21, 2015
Debt Instrument [Line Items]
Net unamortized debt issuance costs	$ (31,824)	$ (34,781)
Less: current maturities of long term debt	(647)	(622)
Long-term debt, net of current maturities	2,100,825	2,038,321
Construction loan
Debt Instrument [Line Items]
Net unamortized debt issuance costs	(100)
6.625% senior unsecured notes due 2023 | Senior notes
Debt Instrument [Line Items]
Long-term debt	350,000	350,000
Net unamortized debt issuance costs	$ (4,600)
Stated interest rate, percent	6.625%						6.625%
6.000% senior unsecured notes due 2024 | Senior notes
Debt Instrument [Line Items]
Long-term debt	$ 650,000	650,000
Net unamortized debt issuance costs	$ (9,000)
Stated interest rate, percent	6.00%				6.00%
6.375% senior unsecured notes due 2025 | Senior notes
Debt Instrument [Line Items]
Long-term debt	$ 600,000	600,000
Net unamortized debt issuance costs	$ (12,900)
Stated interest rate, percent	6.375%			6.375%
6.375% senior unsecured notes due 2026 | Senior notes
Debt Instrument [Line Items]
Long-term debt	$ 450,000	450,000
Net unamortized debt issuance costs	$ (5,200)
Stated interest rate, percent	6.375%		6.375%
Nova Scotia, Amegy, KeyBank | Revolving credit agreement | Revolving credit agreement
Debt Instrument [Line Items]
Long-term debt	$ 60,000	0
InterBank | Revolving credit agreement | Construction loan
Debt Instrument [Line Items]
Stated interest rate, percent						4.50%
InterBank | Letter of credit | Construction loan
Debt Instrument [Line Items]
Long-term debt	$ 23,296	$ 23,724

LONG-TERM DEBT (Narrative) (Det

LONG-TERM DEBT (Narrative) (Details)	May 21, 2018USD ($)	Nov. 21, 2017	May 04, 2017USD ($)bank	Dec. 21, 2016USD ($)	Oct. 14, 2016USD ($)	Jan. 31, 2016	Sep. 30, 2018USD ($)	Sep. 30, 2017USD ($)	Sep. 30, 2018USD ($)	Sep. 30, 2017USD ($)	Dec. 31, 2017USD ($)	Oct. 11, 2017USD ($)	May 05, 2017USD ($)	Mar. 29, 2017USD ($)	Jun. 04, 2015USD ($)	Apr. 21, 2015USD ($)
Debt Instrument [Line Items]
Capitalized interest expense, undeveloped properties							$ 1,600,000	$ 2,100,000	$ 4,000,000	$ 8,800,000
Debt issuance costs, net							31,824,000		31,824,000		$ 34,781,000
Construction loan
Debt Instrument [Line Items]
Debt issuance costs, net							$ 100,000		$ 100,000
Revolving credit agreement | Maximum
Debt Instrument [Line Items]
Debt covenant ratio for future EBITDAX							4		4
Revolving credit agreement | Revolving credit agreement
Debt Instrument [Line Items]
Debt covenant ratio for EBITDAX							3		3
6.000% senior unsecured notes due 2024 | Senior notes
Debt Instrument [Line Items]
Long-term debt							$ 650,000,000		$ 650,000,000		650,000,000
Stated interest rate, percent					6.00%		6.00%		6.00%
Debt instrument, amount					$ 650,000,000
Proceeds from issuance of Senior Notes					$ 638,900,000
Debt issuance costs, net							$ 9,000,000		$ 9,000,000
6.625% senior unsecured notes due 2023 | Senior notes
Debt Instrument [Line Items]
Long-term debt							$ 350,000,000		$ 350,000,000		350,000,000
Stated interest rate, percent							6.625%		6.625%							6.625%
Debt instrument, amount																$ 350,000,000
Long term debt, net of initial purchaser discounts and commissions and estimated offering expenses																$ 343,600,000
Debt issuance costs, net							$ 4,600,000		$ 4,600,000
6.375% senior unsecured notes due 2025 | Senior notes
Debt Instrument [Line Items]
Long-term debt							$ 600,000,000		$ 600,000,000		600,000,000
Stated interest rate, percent				6.375%			6.375%		6.375%
Debt instrument, amount				$ 600,000,000
Proceeds from issuance of Senior Notes				$ 584,700,000
Debt issuance costs, net							$ 12,900,000		$ 12,900,000
6.375% senior unsecured notes due 2026 | Senior notes
Debt Instrument [Line Items]
Long-term debt							$ 450,000,000		$ 450,000,000		450,000,000
Stated interest rate, percent							6.375%		6.375%			6.375%
Debt instrument, amount												$ 450,000,000
Long term debt, net of initial purchaser discounts and commissions and estimated offering expenses												$ 444,100,000
Debt issuance costs, net							$ 5,200,000		$ 5,200,000
Nova Scotia, Amegy, KeyBank | Revolving credit agreement
Debt Instrument [Line Items]
Credit facility interest rate at the eurodollar rate									3.72%
Nova Scotia, Amegy, KeyBank | Revolving credit agreement | Base rate | Minimum
Debt Instrument [Line Items]
Stated interest rate, percent							0.25%		0.25%
Nova Scotia, Amegy, KeyBank | Revolving credit agreement | Base rate | Maximum
Debt Instrument [Line Items]
Stated interest rate, percent							1.25%		1.25%
Nova Scotia, Amegy, KeyBank | Revolving credit agreement | Federal funds rate
Debt Instrument [Line Items]
Basis spread, percent									0.50%
Nova Scotia, Amegy, KeyBank | Revolving credit agreement | Eurodollar rate
Debt Instrument [Line Items]
Basis spread, percent									1.00%
Nova Scotia, Amegy, KeyBank | Revolving credit agreement | Eurodollar rate | Minimum
Debt Instrument [Line Items]
Stated interest rate, percent							1.25%		1.25%
Nova Scotia, Amegy, KeyBank | Revolving credit agreement | Eurodollar rate | Maximum
Debt Instrument [Line Items]
Stated interest rate, percent							2.25%		2.25%
Nova Scotia, Amegy, KeyBank | Revolving credit agreement | Revolving credit agreement
Debt Instrument [Line Items]
Long-term debt							$ 60,000,000		$ 60,000,000		0
Maximum borrowing capacity							1,500,000,000		1,500,000,000
Minimum acquisition payment limit														$ 50,000,000
Minimum disposition of property limit														$ 50,000,000
Borrowing base	$ 1,400,000,000		$ 700,000,000				1,200,000,000		1,200,000,000				$ 1,000,000,000
Number of banks added to syndicate (in banks) | bank			5
Increase (decrease) in interest rate	0.25%	0.50%
Remaining borrowing capacity							623,800,000		623,800,000
Nova Scotia, Amegy, KeyBank | Letter of credit | Revolving credit agreement
Debt Instrument [Line Items]
Line of credit facility, elected commitment	$ 1,000,000,000						1,000,000,000		1,000,000,000
Credit facility outstanding							316,200,000		316,200,000
Disposition costs, maximum expenses allowed									3,000,000
InterBank | Revolving credit agreement | Construction loan
Debt Instrument [Line Items]
Maximum borrowing capacity															$ 24,500,000
Stated interest rate, percent															4.50%
InterBank | Letter of credit | Construction loan
Debt Instrument [Line Items]
Long-term debt							$ 23,296,000		$ 23,296,000		$ 23,724,000
Required minimum down payment, percent						30.00%

COMMON STOCK AND CHANGES IN C_2

COMMON STOCK AND CHANGES IN CAPITALIZATION (Details) - USD ($)	Feb. 17, 2017	Sep. 30, 2018	Sep. 30, 2018	May 31, 2018	Jan. 31, 2018
Class of Stock [Line Items]
Stock repurchase program, amount authorized to acquire					$ 100,000,000
Amount of shares repurchased		$ 5,000,000	$ 109,997,000
Vitruvian acquisition
Class of Stock [Line Items]
Total initial purchase price	$ 1,850,000,000
Payments to acquire businesses	$ 1,354,093,000
Equity interest issued or issuable, number of shares (in shares)	23,900,000
Vitruvian acquisition | Indemnity escrow
Class of Stock [Line Items]
Equity interest issued or issuable, number of shares (in shares)	5,200,000
Common Stock
Class of Stock [Line Items]
Shares repurchased (in shares)		400,000	10,505,469
Amount of shares repurchased			$ 105,000
Minimum
Class of Stock [Line Items]
Stock repurchase program, amount authorized to acquire				$ 100,000,000
Maximum
Class of Stock [Line Items]
Stock repurchase program, amount authorized to acquire				$ 200,000,000

STOCK-BASED COMPENSATION (Narra

STOCK-BASED COMPENSATION (Narrative) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Share-based Compensation [Abstract]
Stock-based compensation cost	$ 3.6	$ 2.8	$ 9.7	$ 8
Capitalized stock-based compensation cost	1.4	$ 1.1	3.9	$ 3.2
Unrecognized compensation expense	$ 15.5		$ 15.5
Weighted average period of expense recognition period			1 year 7 months 17 days

STOCK-BASED COMPENSATION (Restr

STOCK-BASED COMPENSATION (Restricted Stock Award and Unit Activity) (Details) - Restricted Stock	9 Months Ended
	Sep. 30, 2018$ / sharesshares
Number of Unvested Restricted Shares
Unvested shares, beginning balance (in shares) | shares	976,027
Granted (in shares) | shares	1,197,628
Vested (in shares) | shares	(618,202)
Forfeited (in shares) | shares	(32,633)
Unvested shares, ending balance (in shares) | shares	1,522,820
Weighted Average Grant Date Fair Value
Unvested shares, beginning balance (in dollars per share) | $ / shares	$ 18.71
Granted (in dollars per share) | $ / shares	9.45
Vested (in dollars per share) | $ / shares	17.77
Forfeited (in dollars per share) | $ / shares	17.31
Unvested shares, ending balance (in dollars per share) | $ / shares	$ 11.84

EARNINGS PER SHARE (Details)

EARNINGS PER SHARE (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Basic:
Net income - basic	$ 95,150	$ 18,235	$ 296,559	$ 278,626
Net income - basic (in shares)	173,057,538	182,957,416	175,776,312	178,736,569
Net income - basic (in usd per share)	$ 0.55	$ 0.10	$ 1.69	$ 1.56
Effect of dilutive securities:
Stock options and awards	$ 0	$ 0	$ 0	$ 0
Stock options and awards (in shares)	247,376	51,020	664,149	394,001
Diluted:
Net income - diluted	$ 95,150	$ 18,235	$ 296,559	$ 278,626
Net income - diluted (in shares)	173,304,914	183,008,436	176,440,461	179,130,570
Net income - diluted (in usd per share)	$ 0.55	$ 0.10	$ 1.68	$ 1.56

COMMITTMENTS AND CONTINGENCIE_2

COMMITTMENTS AND CONTINGENCIES (Narrative) (Details)	Jul. 29, 2016complaintdefendant	Feb. 09, 2016complaintdefendant	Mar. 11, 1997	Sep. 30, 2018USD ($)well	Jul. 29, 2016complaint	Sep. 30, 2018USD ($)well	Sep. 30, 2017USD ($)	Dec. 31, 1997USD ($)well
Commitments [Line Items]
Plugging and abandonment trust on the WCBB properties				$ 3,100,000		$ 3,100,000
Number of claims filed (in claims) | complaint					2
Judicial District Court for the Parish of Cameron
Commitments [Line Items]
Number of claims filed (in claims) | complaint		1
Number of defendants (in defendants) | defendant		26
Judicial District Court for the Parish of Vermillion
Commitments [Line Items]
Number of claims filed (in claims) | complaint	1
Number of defendants (in defendants) | defendant	40
Purchase commitment
Commitments [Line Items]
Future minimum commitments				154,200,000		154,200,000
Transportation commitment
Commitments [Line Items]
Firm transportation contracted with third parties				3,566,330,000		3,566,330,000
Future minimum commitments				62,012,000		62,012,000
Loss on long-term purchase commitment | Muskie Proppant LLC
Commitments [Line Items]
Non-utilization fees, accrued damages year to date				$ 1,300,000		$ 1,500,000	$ 0
Minimum
Commitments [Line Items]
Operating lease, term (in years)				1 year		1 year
WCBB
Commitments [Line Items]
Remaining interest in oil and gas property acquisition, percent								50.00%
Payments of seller's obligation to contribute								$ 18,000
Minimum number of wells to be plugged (in wells) | well								20
Tenure of minimum wells to be plugged (in years)			20 years
Number of wells plugged (in wells) | well				555		555

COMMITTMENTS AND CONTINGENCIE_3

COMMITTMENTS AND CONTINGENCIES (Future Commitments) (Details) $ in Thousands	Sep. 30, 2018USD ($)MMBTU
Remaining 2,018	$ 39
2,019	144
2,020	90
2,021	38
Total	$ 311
Remaining 2018 (in mmbtu) | MMBTU	590,000
2019 (in mmbtu) | MMBTU	659,000
2020 (in mmbtu) | MMBTU	526,000
2021 (in mmbtu) | MMBTU	372,000
2022 (in mmbtu) | MMBTU	272,000
Thereafter (in mmbtu) | MMBTU	240,000
Total (in mmbtu) | MMBTU	2,659,000
Transportation commitment
Remaining 2,018	$ 62,012
2,019	251,644
2,020	247,581
2,021	246,620
2,022	246,620
Thereafter	2,511,853
Total	$ 3,566,330

DERIVATIVE INSTRUMENTS (Narrati

DERIVATIVE INSTRUMENTS (Narrative) (Details) - 2019	9 Months Ended
	Sep. 30, 2018MMBTU$ / MMBTU
Derivative [Line Items]
Daily volume (in MMBtu) | MMBTU	100,000
Weighted average price (in usd per MMBtu or Bbl) | $ / MMBTU	3.05

DERIVATIVE INSTRUMENTS (Schedul

DERIVATIVE INSTRUMENTS (Schedule of Derivative Instruments) (Details)	9 Months Ended
	Sep. 30, 2018MMBTU$ / bbl$ / MMBTUbbl
NYMEX Henry Hub Swap - 2018
Derivative [Line Items]
Daily Volume (MMBtu/day) | MMBTU	1,010,000
Weighted average price (in usd per MMBtu or Bbl) | $ / MMBTU	3.01
NYMEX Henry Hub Swap - 2018 | Short | Call Option
Derivative [Line Items]
Daily Volume (MMBtu/day) | MMBTU	50,000
Weighted average price (in usd per MMBtu or Bbl) | $ / MMBTU	3.13
NYMEX Henry Hub Swap - 2019
Derivative [Line Items]
Daily Volume (MMBtu/day) | MMBTU	1,154,000
Weighted average price (in usd per MMBtu or Bbl) | $ / MMBTU	2.81
NYMEX Henry Hub Swap - 2019 | Short | Call Option
Derivative [Line Items]
Daily Volume (MMBtu/day) | MMBTU	30,000
Weighted average price (in usd per MMBtu or Bbl) | $ / MMBTU	3.10
NYMEX Henry Hub Swap - 2020
Derivative [Line Items]
Daily Volume (MMBtu/day) | MMBTU	204,000
Weighted average price (in usd per MMBtu or Bbl) | $ / MMBTU	2.77
ARGUS LLS Swap - 2018
Derivative [Line Items]
Daily Volume (Bbls/day) | bbl	2,000
Weighted average price (in usd per MMBtu or Bbl) | $ / bbl	56.22
ARGUS LLS Swap - 2019
Derivative [Line Items]
Daily Volume (Bbls/day) | bbl	1,000
Weighted average price (in usd per MMBtu or Bbl) | $ / bbl	59.55
NYMEX WTI Swap - 2018
Derivative [Line Items]
Daily Volume (Bbls/day) | bbl	4,500
Weighted average price (in usd per MMBtu or Bbl) | $ / bbl	53.72
NYMEX WTI Swap - 2019
Derivative [Line Items]
Daily Volume (Bbls/day) | bbl	4,000
Weighted average price (in usd per MMBtu or Bbl) | $ / bbl	58.28
Mont Belvieu C2 - 2019
Derivative [Line Items]
Daily Volume (Bbls/day) | bbl	1,000
Weighted average price (in usd per MMBtu or Bbl) | $ / bbl	18.48
Mont Belvieu C3 Swap - 2018
Derivative [Line Items]
Daily Volume (Bbls/day) | bbl	4,000
Weighted average price (in usd per MMBtu or Bbl) | $ / bbl	29.34
Mont Belvieu C3 Swap - 2019
Derivative [Line Items]
Daily Volume (Bbls/day) | bbl	4,000
Weighted average price (in usd per MMBtu or Bbl) | $ / bbl	28.87
Mont Belvieu C5 Swap - 2018
Derivative [Line Items]
Daily Volume (Bbls/day) | bbl	500
Weighted average price (in usd per MMBtu or Bbl) | $ / bbl	46.62
Mont Belvieu C5 Swap - 2019
Derivative [Line Items]
Daily Volume (Bbls/day) | bbl	500
Weighted average price (in usd per MMBtu or Bbl) | $ / bbl	54.08
Transco Zone 4 - 2018 | Long
Derivative [Line Items]
Daily Volume (MMBtu/day) | MMBTU	40,000
Weighted average price (in usd per MMBtu or Bbl) | $ / MMBTU	0.05
Transco Zone 4 - 2019 | Long
Derivative [Line Items]
Daily Volume (MMBtu/day) | MMBTU	60,000
Weighted average price (in usd per MMBtu or Bbl) | $ / MMBTU	0.05
Transco Zone 4 - 2020 | Long
Derivative [Line Items]
Daily Volume (MMBtu/day) | MMBTU	60,000
Weighted average price (in usd per MMBtu or Bbl) | $ / MMBTU	0.05

DERIVATIVE INSTRUMENTS (Derivat

DERIVATIVE INSTRUMENTS (Derivative Instruments in Financial Position) (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
General Discussion of Derivative Instruments and Hedging Activities [Abstract]
Short-term derivative instruments - asset	$ 19,809	$ 78,847
Long-term derivative instruments - asset	3,530	8,685
Short-term derivative instruments - liability	62,601	32,534
Long-term derivative instruments - liability	$ 15,101	$ 2,989

DERIVATIVE INSTRUMENTS (Net (Lo

DERIVATIVE INSTRUMENTS (Net (Loss) Gain on Derivative Instruments) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Derivative [Line Items]
Net (loss) gain on natural gas, oil, and NGL derivatives	$ (9,663)	$ (22,860)	$ (96,737)	$ 141,588
Natural gas derivatives
Derivative [Line Items]
Net (loss) gain on natural gas, oil, and NGL derivatives	14,101	(7,077)	(26,789)	135,868
Oil derivatives
Derivative [Line Items]
Net (loss) gain on natural gas, oil, and NGL derivatives	(11,610)	(6,571)	(45,176)	12,477
Natural gas liquids derivatives
Derivative [Line Items]
Net (loss) gain on natural gas, oil, and NGL derivatives	$ (12,154)	$ (9,212)	$ (24,772)	$ (6,757)

DERIVATIVE INSTRUMENTS (Sched_2

DERIVATIVE INSTRUMENTS (Schedule of Offsetting) (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Gross assets presented in the consolidated balance sheet	$ 23,339	$ 87,532
Gross assets subject to mater netting agreement - assets	(17,053)	(22,199)
Net amount - assets	6,286	65,333
Gross liabilities presented in the consolidated balance sheet	(77,702)	(35,523)
Gross amounts subject to master netting agreement - liabilities	17,053	22,199
Net amount - liabilities	$ (60,649)	$ (13,324)

FAIR VALUE MEASUREMENTS (Detail

FAIR VALUE MEASUREMENTS (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017
Liabilities:
Asset retirement obligation capitalized	$ 1,468	$ 11,557
Level 1
Assets:
Derivative Instruments	0		$ 0
Liabilities:
Derivative Instruments	0		0
Level 2
Assets:
Derivative Instruments	23,339		87,532
Liabilities:
Derivative Instruments	77,702		35,523
Level 3
Assets:
Derivative Instruments	0		0
Liabilities:
Derivative Instruments	$ 0		$ 0

FAIR VALUE OF FINANCIAL INSTR_2

FAIR VALUE OF FINANCIAL INSTRUMENTS (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Debt Instrument [Line Items]
Unamortized debt issuance costs	$ 31,824	$ 34,781
Senior notes | 6.625% senior unsecured notes due 2023
Debt Instrument [Line Items]
Unamortized debt issuance costs	4,600
Senior notes | 6.000% senior unsecured notes due 2024
Debt Instrument [Line Items]
Unamortized debt issuance costs	9,000
Senior notes | 6.375% senior unsecured notes due 2025
Debt Instrument [Line Items]
Unamortized debt issuance costs	12,900
Senior notes | 6.375% senior unsecured notes due 2026
Debt Instrument [Line Items]
Unamortized debt issuance costs	5,200
Carry value | Senior notes
Debt Instrument [Line Items]
Carrying value of notes	2,000,000
Fair value | Senior notes
Debt Instrument [Line Items]
Carrying value of notes	$ 2,000,000

REVENUE FROM CONTRACTS WITH C_2

REVENUE FROM CONTRACTS WITH CUSTOMERS (Details) - USD ($) $ in Millions	Sep. 30, 2018	Dec. 31, 2017
Revenue from Contract with Customer [Abstract]
Receivables from contracts with customers	$ 157.4	$ 146.8

CONDENSED CONSOLIDATING FINAN_3

CONDENSED CONSOLIDATING FINANCIAL INFORMATION (Narrative) (Details) - Senior notes - USD ($)	Oct. 11, 2017	Dec. 21, 2016	Oct. 14, 2016	Apr. 21, 2015
6.625% senior unsecured notes due 2023
Condensed Financial Statements, Captions [Line Items]
Debt instrument, amount				$ 350,000,000
6.000% senior unsecured notes due 2024
Condensed Financial Statements, Captions [Line Items]
Debt instrument, amount			$ 650,000,000
6.375% senior unsecured notes due 2025
Condensed Financial Statements, Captions [Line Items]
Debt instrument, amount		$ 600,000,000
6.375% senior unsecured notes due 2026
Condensed Financial Statements, Captions [Line Items]
Debt instrument, amount	$ 450,000,000

CONDENSED CONSOLIDATING FINAN_4

CONDENSED CONSOLIDATING FINANCIAL INFORMATION (Balance Sheets) (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017	Sep. 30, 2017	Dec. 31, 2016
Current assets:
Cash and cash equivalents	$ 124,571	$ 99,557
Accounts receivable - oil and natural gas sales	157,391	146,773
Accounts receivable - joint interest and other	39,511	35,440
Accounts receivable - related parties	79	0
Accounts receivable - intercompany	0	0
Prepaid expenses and other current assets	9,742	4,912
Short-term derivative instruments	19,809	78,847
Total current assets	351,103	365,529
Property and equipment:
Oil and natural gas properties	9,936,714	9,169,156
Other property and equipment	92,388	86,754
Accumulated depletion, depreciation, amortization and impairment	(4,506,306)	(4,153,733)
Property and equipment, net	5,522,796	5,102,177
Other assets:
Equity investments and investments in subsidiaries	232,529	302,112
Long-term derivative instruments	3,530	8,685
Deferred tax asset	0	1,208
Inventories	8,234	8,227
Other assets	17,038	19,814
Total other assets	261,331	340,046
Total assets	6,135,230	5,807,752
Current liabilities:
Accounts payable and accrued liabilities	582,464	553,609
Accounts payable - intercompany	0	0
Asset retirement obligation—current	120	120	$ 195
Short-term derivative instruments	62,601	32,534
Current maturities of long-term debt	647	622
Total current liabilities	645,832	586,885
Long-term derivative instruments	15,101	2,989
Asset retirement obligation—long-term	78,411	74,980	44,266
Deferred tax liability	3,046	0
Other non-current liabilities	0	2,963
Long-term debt, net of current maturities	2,100,825	2,038,321
Total liabilities	2,843,215	2,706,138
Stockholders’ equity:
Common stock	1,732	1,831
Paid-in capital	4,316,006	4,416,250
Accumulated other comprehensive (loss) income	(46,354)	(40,539)
Retained (deficit) earnings	(979,369)	(1,275,928)
Total stockholders’ equity	3,292,015	3,101,614	$ 2,942,661	$ 2,183,892
Total liabilities and stockholders’ equity	6,135,230	5,807,752
Reportable legal entities | Parent
Current assets:
Cash and cash equivalents	89,214	67,908
Accounts receivable - oil and natural gas sales	111,463	112,686
Accounts receivable - joint interest and other	19,066	15,435
Accounts receivable - related parties	79
Accounts receivable - intercompany	662,319	554,439
Prepaid expenses and other current assets	7,521	4,719
Short-term derivative instruments	19,809	78,847
Total current assets	909,471	834,034
Property and equipment:
Oil and natural gas properties	7,003,396	6,562,147
Other property and equipment	91,637	86,711
Accumulated depletion, depreciation, amortization and impairment	(4,506,267)	(4,153,696)
Property and equipment, net	2,588,766	2,495,162
Other assets:
Equity investments and investments in subsidiaries	2,723,140	2,361,575
Long-term derivative instruments	3,530	8,685
Deferred tax asset		1,208
Inventories	6,800	5,816
Other assets	13,018	12,483
Total other assets	2,746,488	2,389,767
Total assets	6,244,725	5,718,963
Current liabilities:
Accounts payable and accrued liabilities	464,426	416,249
Accounts payable - intercompany	240,310	63,373
Asset retirement obligation—current	120	120
Short-term derivative instruments	62,601	32,534
Current maturities of long-term debt	647	622
Total current liabilities	768,104	512,898
Long-term derivative instruments	15,101	2,989
Asset retirement obligation—long-term	65,634	63,141
Deferred tax liability	3,046
Other non-current liabilities		0
Long-term debt, net of current maturities	2,100,825	2,038,321
Total liabilities	2,952,710	2,617,349
Stockholders’ equity:
Common stock	1,732	1,831
Paid-in capital	4,316,006	4,416,250
Accumulated other comprehensive (loss) income	(46,354)	(40,539)
Retained (deficit) earnings	(979,369)	(1,275,928)
Total stockholders’ equity	3,292,015	3,101,614
Total liabilities and stockholders’ equity	6,244,725	5,718,963
Reportable legal entities | Guarantors
Current assets:
Cash and cash equivalents	35,357	31,649
Accounts receivable - oil and natural gas sales	45,928	34,087
Accounts receivable - joint interest and other	20,445	20,005
Accounts receivable - related parties	0
Accounts receivable - intercompany	240,373	63,374
Prepaid expenses and other current assets	2,221	193
Short-term derivative instruments	0	0
Total current assets	344,324	149,308
Property and equipment:
Oil and natural gas properties	2,934,047	2,607,738
Other property and equipment	751	43
Accumulated depletion, depreciation, amortization and impairment	(39)	(37)
Property and equipment, net	2,934,759	2,607,744
Other assets:
Equity investments and investments in subsidiaries		77,744
Long-term derivative instruments	0	0
Deferred tax asset		0
Inventories	1,434	2,411
Other assets	4,020	7,331
Total other assets	5,454	87,486
Total assets	3,284,537	2,844,538
Current liabilities:
Accounts payable and accrued liabilities	118,038	137,361
Accounts payable - intercompany	662,254	554,313
Asset retirement obligation—current	0	0
Short-term derivative instruments	0	0
Current maturities of long-term debt	0	0
Total current liabilities	780,292	691,674
Long-term derivative instruments	0	0
Asset retirement obligation—long-term	12,777	11,839
Deferred tax liability	0
Other non-current liabilities		2,963
Long-term debt, net of current maturities	0	0
Total liabilities	793,069	706,476
Stockholders’ equity:
Common stock	0	0
Paid-in capital	1,915,598	1,915,598
Accumulated other comprehensive (loss) income	0	0
Retained (deficit) earnings	575,870	222,464
Total stockholders’ equity	2,491,468	2,138,062
Total liabilities and stockholders’ equity	3,284,537	2,844,538
Reportable legal entities | Non-Guarantor
Current assets:
Cash and cash equivalents	0	0
Accounts receivable - oil and natural gas sales	0	0
Accounts receivable - joint interest and other	0	0
Accounts receivable - related parties	0
Accounts receivable - intercompany	0	0
Prepaid expenses and other current assets	0	0
Short-term derivative instruments	0	0
Total current assets	0	0
Property and equipment:
Oil and natural gas properties	0	0
Other property and equipment	0	0
Accumulated depletion, depreciation, amortization and impairment	0	0
Property and equipment, net	0	0
Other assets:
Equity investments and investments in subsidiaries	53,380	57,641
Long-term derivative instruments	0	0
Deferred tax asset		0
Inventories	0	0
Other assets	0	0
Total other assets	53,380	57,641
Total assets	53,380	57,641
Current liabilities:
Accounts payable and accrued liabilities	0	0
Accounts payable - intercompany	128	127
Asset retirement obligation—current	0	0
Short-term derivative instruments	0	0
Current maturities of long-term debt	0	0
Total current liabilities	128	127
Long-term derivative instruments	0	0
Asset retirement obligation—long-term	0	0
Deferred tax liability	0
Other non-current liabilities		0
Long-term debt, net of current maturities	0	0
Total liabilities	128	127
Stockholders’ equity:
Common stock	0	0
Paid-in capital	261,626	259,307
Accumulated other comprehensive (loss) income	(44,338)	(38,593)
Retained (deficit) earnings	(164,036)	(163,200)
Total stockholders’ equity	53,252	57,514
Total liabilities and stockholders’ equity	53,380	57,641
Eliminations
Current assets:
Cash and cash equivalents	0	0
Accounts receivable - oil and natural gas sales	0	0
Accounts receivable - joint interest and other	0	0
Accounts receivable - related parties	0
Accounts receivable - intercompany	(902,692)	(617,813)
Prepaid expenses and other current assets	0	0
Short-term derivative instruments	0	0
Total current assets	(902,692)	(617,813)
Property and equipment:
Oil and natural gas properties	(729)	(729)
Other property and equipment	0	0
Accumulated depletion, depreciation, amortization and impairment	0	0
Property and equipment, net	(729)	(729)
Other assets:
Equity investments and investments in subsidiaries	(2,543,991)	(2,194,848)
Long-term derivative instruments	0	0
Deferred tax asset		0
Inventories	0	0
Other assets	0	0
Total other assets	(2,543,991)	(2,194,848)
Total assets	(3,447,412)	(2,813,390)
Current liabilities:
Accounts payable and accrued liabilities	0	(1)
Accounts payable - intercompany	(902,692)	(617,813)
Asset retirement obligation—current	0	0
Short-term derivative instruments	0	0
Current maturities of long-term debt	0	0
Total current liabilities	(902,692)	(617,814)
Long-term derivative instruments	0	0
Asset retirement obligation—long-term	0	0
Deferred tax liability	0
Other non-current liabilities		0
Long-term debt, net of current maturities	0	0
Total liabilities	(902,692)	(617,814)
Stockholders’ equity:
Common stock	0	0
Paid-in capital	(2,177,224)	(2,174,905)
Accumulated other comprehensive (loss) income	44,338	38,593
Retained (deficit) earnings	(411,834)	(59,264)
Total stockholders’ equity	(2,544,720)	(2,195,576)
Total liabilities and stockholders’ equity	$ (3,447,412)	$ (2,813,390)

CONDENSED CONSOLIDATING FINAN_5

CONDENSED CONSOLIDATING FINANCIAL INFORMATION (Statements of Operations) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Revenues:
Total revenues	$ 360,962	$ 265,498	$ 939,094	$ 922,455
Costs and expenses:
Lease operating expenses	22,325	20,020	64,143	60,044
Production taxes	9,348	5,419	23,861	14,464
Midstream gathering and processing	78,913	69,372	214,546	176,258
Depreciation, depletion and amortization	119,915	106,650	352,848	254,887
General and administrative	15,848	13,065	42,955	37,922
Accretion expense	1,037	456	3,056	1,148
Acquisition expense	0	33	0	2,391
Total costs and expenses	247,386	215,015	701,409	547,114
INCOME (LOSS) FROM OPERATIONS	113,576	50,483	237,685	375,341
OTHER (INCOME) EXPENSE:
Interest expense	33,253	27,130	100,922	74,797
Interest income	(92)	(37)	(162)	(927)
Litigation settlement	917	0	917	0
Insurance proceeds	0	0	(231)	0
Gain on sale of equity method investments	(2,733)	0	(124,768)	(12,523)
(Income) loss from equity method investments and investments in subsidiaries	(12,858)	2,737	(35,282)	33,468
Other income	(61)	(345)	(201)	(863)
Total other (income) expense	18,426	29,485	(58,805)	93,952
INCOME (LOSS) BEFORE INCOME TAXES	95,150	20,998	296,490	281,389
INCOME TAX BENEFIT	0	2,763	(69)	2,763
NET INCOME (LOSS)	95,150	18,235	296,559	278,626
Parent
OTHER (INCOME) EXPENSE:
Insurance proceeds			(231)
Guarantors
OTHER (INCOME) EXPENSE:
Litigation settlement			0
Insurance proceeds			0
Non-Guarantor
OTHER (INCOME) EXPENSE:
Litigation settlement			0
Insurance proceeds			0
Reportable legal entities | Parent
Revenues:
Total revenues	235,683	188,390	596,018	710,184
Costs and expenses:
Lease operating expenses	16,502	16,019	46,926	49,891
Production taxes	4,505	4,052	13,309	10,799
Midstream gathering and processing	54,397	52,725	152,605	132,740
Depreciation, depletion and amortization	119,914	106,649	352,846	254,884
General and administrative	16,314	13,956	45,100	39,882
Accretion expense	812	335	2,397	908
Acquisition expense		(5)		0
Total costs and expenses	212,444	193,731	613,183	489,104
INCOME (LOSS) FROM OPERATIONS	23,239	(5,341)	(17,165)	221,080
OTHER (INCOME) EXPENSE:
Interest expense	34,254	27,914	103,310	79,095
Interest income	(86)	(29)	(144)	(913)
Litigation settlement	917		917
Gain on sale of equity method investments	(2,733)		(28,349)	(12,523)
(Income) loss from equity method investments and investments in subsidiaries	(104,226)	(53,880)	(387,991)	(124,446)
Other income	(37)	(344)	(1,167)	(1,522)
Total other (income) expense	(71,911)	(26,339)	(313,655)	(60,309)
INCOME (LOSS) BEFORE INCOME TAXES	95,150	20,998	296,490	281,389
INCOME TAX BENEFIT	0	2,763	(69)	2,763
NET INCOME (LOSS)	95,150	18,235	296,559	278,626
Reportable legal entities | Guarantors
Revenues:
Total revenues	125,279	77,108	343,076	212,271
Costs and expenses:
Lease operating expenses	5,823	4,001	17,217	10,153
Production taxes	4,843	1,367	10,552	3,665
Midstream gathering and processing	24,516	16,647	61,941	43,518
Depreciation, depletion and amortization	1	1	2	3
General and administrative	(467)	(892)	(2,148)	(1,963)
Accretion expense	225	121	659	240
Acquisition expense		38		2,391
Total costs and expenses	34,941	21,283	88,223	58,007
INCOME (LOSS) FROM OPERATIONS	90,338	55,825	254,853	154,264
OTHER (INCOME) EXPENSE:
Interest expense	(1,001)	(784)	(2,388)	(4,298)
Interest income	(6)	(8)	(18)	(14)
Litigation settlement	0
Gain on sale of equity method investments	0		(96,419)	0
(Income) loss from equity method investments and investments in subsidiaries	(1)	128	(694)	2,586
Other income	(24)	(1)	(34)	(241)
Total other (income) expense	(1,032)	(665)	(99,553)	(1,967)
INCOME (LOSS) BEFORE INCOME TAXES	91,370	56,490	354,406	156,231
INCOME TAX BENEFIT	0	0	0	0
NET INCOME (LOSS)	91,370	56,490	354,406	156,231
Reportable legal entities | Non-Guarantor
Revenues:
Total revenues	0	0	0	0
Costs and expenses:
Lease operating expenses	0	0	0	0
Production taxes	0	0	0	0
Midstream gathering and processing	0	0	0	0
Depreciation, depletion and amortization	0	0	0	0
General and administrative	1	1	3	3
Accretion expense	0	0	0	0
Acquisition expense		0		0
Total costs and expenses	1	1	3	3
INCOME (LOSS) FROM OPERATIONS	(1)	(1)	(3)	(3)
OTHER (INCOME) EXPENSE:
Interest expense	0	0	0	0
Interest income	0	0	0	0
Litigation settlement	0
Gain on sale of equity method investments	0		0	0
(Income) loss from equity method investments and investments in subsidiaries	275	296	833	869
Other income	0	0	0	0
Total other (income) expense	275	296	833	869
INCOME (LOSS) BEFORE INCOME TAXES	(276)	(297)	(836)	(872)
INCOME TAX BENEFIT	0	0	0	0
NET INCOME (LOSS)	(276)	(297)	(836)	(872)
Eliminations
Revenues:
Total revenues	0	0	0	0
Costs and expenses:
Lease operating expenses	0	0	0	0
Production taxes	0	0	0	0
Midstream gathering and processing	0	0	0	0
Depreciation, depletion and amortization	0	0	0	0
General and administrative	0	0	0	0
Accretion expense	0	0	0	0
Acquisition expense		0		0
Total costs and expenses	0	0	0	0
INCOME (LOSS) FROM OPERATIONS	0	0	0	0
OTHER (INCOME) EXPENSE:
Interest expense	0	0	0	0
Interest income	0	0	0	0
Litigation settlement	0		0
Insurance proceeds			0
Gain on sale of equity method investments	0		0	0
(Income) loss from equity method investments and investments in subsidiaries	91,094	56,193	352,570	154,459
Other income	0	0	1,000	900
Total other (income) expense	91,094	56,193	353,570	155,359
INCOME (LOSS) BEFORE INCOME TAXES	(91,094)	(56,193)	(353,570)	(155,359)
INCOME TAX BENEFIT	0	0	0	0
NET INCOME (LOSS)	$ (91,094)	$ (56,193)	$ (353,570)	$ (155,359)

CONDENSED CONSOLIDATING FINAN_6

CONDENSED CONSOLIDATING FINANCIAL INFORMATION (Statements of Comprehensive Income (Loss)) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Condensed Financial Statements, Captions [Line Items]
Net income (loss)	$ 95,150	$ 18,235	$ 296,559	$ 278,626
Foreign currency translation adjustment	3,052	6,832	(5,815)	12,719
Other comprehensive income (loss)	3,052	6,832	(5,815)	12,719
Comprehensive income	98,202	25,067	290,744	291,345
Reportable legal entities | Parent
Condensed Financial Statements, Captions [Line Items]
Net income (loss)	95,150	18,235	296,559	278,626
Foreign currency translation adjustment	3,052	6,832	(5,815)	12,719
Other comprehensive income (loss)	3,052	6,832	(5,815)	12,719
Comprehensive income	98,202	25,067	290,744	291,345
Reportable legal entities | Guarantors
Condensed Financial Statements, Captions [Line Items]
Net income (loss)	91,370	56,490	354,406	156,231
Foreign currency translation adjustment	103	158	(70)	232
Other comprehensive income (loss)	103	158	(70)	232
Comprehensive income	91,473	56,648	354,336	156,463
Reportable legal entities | Non-Guarantor
Condensed Financial Statements, Captions [Line Items]
Net income (loss)	(276)	(297)	(836)	(872)
Foreign currency translation adjustment	2,949	6,674	(5,745)	12,487
Other comprehensive income (loss)	2,949	6,674	(5,745)	12,487
Comprehensive income	2,673	6,377	(6,581)	11,615
Eliminations
Condensed Financial Statements, Captions [Line Items]
Net income (loss)	(91,094)	(56,193)	(353,570)	(155,359)
Foreign currency translation adjustment	(3,052)	(6,832)	5,815	(12,719)
Other comprehensive income (loss)	(3,052)	(6,832)	5,815	(12,719)
Comprehensive income	$ (94,146)	$ (63,025)	$ (347,755)	$ (168,078)

CONDENSED CONSOLIDATING FINAN_7

CONDENSED CONSOLIDATING FINANCIAL INFORMATION (Cash Flows) (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017
Condensed Financial Statements, Captions [Line Items]
Net cash provided by (used in) operating activities	$ 608,956	$ 491,733
Net cash (used in) provided by investing activities	(532,745)	(2,181,480)
Net cash (used in) provided by financing activities	(51,197)	354,143
Net increase (decrease) in cash, cash equivalents and restricted cash	25,014	(1,335,604)
Cash, cash equivalents and restricted cash at beginning of period	99,557	1,460,875
Cash, cash equivalents and restricted cash at end of period	124,571	125,271
Reportable legal entities | Parent
Condensed Financial Statements, Captions [Line Items]
Net cash provided by (used in) operating activities	416,833	310,624
Net cash (used in) provided by investing activities	(344,330)	(2,034,554)
Net cash (used in) provided by financing activities	(51,197)	354,143
Net increase (decrease) in cash, cash equivalents and restricted cash	21,306	(1,369,787)
Cash, cash equivalents and restricted cash at beginning of period	67,908	1,458,882
Cash, cash equivalents and restricted cash at end of period	89,214	89,095
Reportable legal entities | Guarantors
Condensed Financial Statements, Captions [Line Items]
Net cash provided by (used in) operating activities	192,123	181,108
Net cash (used in) provided by investing activities	(188,415)	(1,554,063)
Net cash (used in) provided by financing activities	0	1,407,137
Net increase (decrease) in cash, cash equivalents and restricted cash	3,708	34,182
Cash, cash equivalents and restricted cash at beginning of period	31,649	1,993
Cash, cash equivalents and restricted cash at end of period	35,357	36,175
Reportable legal entities | Non-Guarantor
Condensed Financial Statements, Captions [Line Items]
Net cash provided by (used in) operating activities	(1)	(1)
Net cash (used in) provided by investing activities	(2,318)	(1,843)
Net cash (used in) provided by financing activities	2,319	1,845
Net increase (decrease) in cash, cash equivalents and restricted cash	0	1
Cash, cash equivalents and restricted cash at beginning of period	0	0
Cash, cash equivalents and restricted cash at end of period	0	1
Eliminations
Condensed Financial Statements, Captions [Line Items]
Net cash provided by (used in) operating activities	1	2
Net cash (used in) provided by investing activities	2,318	1,408,980
Net cash (used in) provided by financing activities	(2,319)	(1,408,982)
Net increase (decrease) in cash, cash equivalents and restricted cash	0	0
Cash, cash equivalents and restricted cash at beginning of period	0	0
Cash, cash equivalents and restricted cash at end of period	$ 0	$ 0

RECENT ACCOUNTING PRONOUNCEME_3

RECENT ACCOUNTING PRONOUNCEMENTS (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Increase to net cash used in investing activities	$ (532,745)	$ (2,181,480)
Accounting Standards Update 2016-18
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Increase to net cash used in investing activities		185,000
Increase in restricted cash		$ 185,000

SUBSEQUENT EVENTS (Details)

SUBSEQUENT EVENTS (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017
Subsequent Events [Abstract]
Accounts receivable—related parties	$ 79	$ 0